Well, apparently I have been successful. I had trouble getting Thomas An's scene to work, but that was because I was too lazy to re-download it to my manager computer. I will try getting that to run next. I ran an old RC5 scene, so ignore the materials, lighting, etc. The basic idea is that it freaking worked. I am amazed - I have a knack for brute forcing my way through this stuff, usually ending with hangs, crashes and smoke.
Here is my test.
Mac Rendering Network
1) G4 dual 1.0 GHz PowerPC, using V 1.1 (original license)
2) MacBook Pro, Intel Core Duo 2.16 GHz, using V 1.1 (plusone license)
Connected over the office intranet. We have PC/Microsoft-based servers and networking/network volumes.
The G4 desktop (represented below by the "$" prompt) was the manager, with the file to be rendered on a local drive for that machine. This machine was also designated a server. This is the machine that I used to launch mxcl -d ("Viewer") to open the MXS and add the job.
The MacBook Pro (represented below by the "%" prompt) was a server.
A network drive was used for the output (test.tga) and the mxi (test.mxi).
The below assumes you have navigated to the directory containing your "mxcl" app typically contained in
/Applications/Maxwell/maxwell.app/Contents/MacOS
I have not added mxcl to my PATH environment variable yet.
It is advised that you use Activity Viewer (Applications> Utilities> Activity Viewer.app) or the shell command "top" to check your process and processor activity.
Step-by-step approach:
1) Open a terminal shell and start the server on the MacBook Pro
% ./mxcl -server
-- you should see the terminal window give you feedback that mxcl has started in server mode
2) open a terminal shell and start the manager on the G4
$ ./mxcl -manager
-- you should see the terminal window give you feedback that mxcl has started in manager mode
3) In a new shell start the server on the G4
$ ./mxcl -server
-- you should see the terminal window give you feedback that mxcl has started in server mode
4) Start the Viewer on the G4
$./mxcl -d
-- the typical viewer GUI should open. This is where you will be doing the "Add Job" step later.
5) Start the Viewer on the MacBook Pro
EDIT: After further testing, this step appears unnecessary
% ./mxcl -d
-- the typical viewer GUI should open.
6) In the Viewer app on the MacBook Pro, click on the "Connect" button in the Network tab panel.
EDIT: After further testing, this step appears unnecessary
-- You will be connected if all goes well and you should see both of your machine IP addresses in the "Render Farm" list, with the "Connected" status in green. So far, so good.
7) In the Viewer app on the G4, click on the "Connect" button in the Network tab panel.
-- You will be connected if all goes well and you should see both of your machine IP addresses in the "Render Farm" list, with the "Connected" status in green. So far, so good. Some times I got a crazy sequence of "Connected/Disconnected" messages in an infinite loop - the shell window said something about the Local Host refusing the connection. If this happens, try quitting the Viewer and relaunching it and repeating Step 7 (use the bang [!] or up arrow in the shell for a quick repeat of the previous command in that shell window [./mxcl -d]).
Eight) Now, in the Viewer on the G4 (the manager machine) choose:
File >> Open MXS and navigate to the local MXS file you wish to Net Render. Select and open it. Incidentally, the actual digit "eight" followed by a close parenthesis makes a smiley like this

.
9) In the "Render Options" Tab of the Viewer, make sure you set your options, most importantly the Output Image Settings and the MXI settings - set these to a NETWORK DRIVE. I have no idea if both or either actually NEED to be set to a netwrok location - I will leave that as an exercise for you.
10) In the Viewer on the G4 (manager machine) go to the Network Tab and choose "Add Job". The dialog that comes up should already have the MXS file you just opened in the "MXS File" input field and all of the Command Line options should be there as well. IMPORTANT: Tick the "Cooperative" Checkbox.
11) Hit the "OK" button and pray.
-- You should see the job listed in the "Jobs" Window - if you click on the expander "+" next to the job, you can see each node of the render farm doing its thing. The SL did not update for my job. The "State" field will update to tell you about what is going on. Essentially each node will render (you can see what is happening in the shell where you gave the "./mxcl -server" command) and then wait to assemble the MXI and final image. Both of these files are output to the netwrok drive location you specified in Step 9.
Once all the nodes are finished the final image will be generated and you should get the state of each node updated to "Success". Congratulate yourself and go have a cold one.
Here are some screengrabs:

"I can't believe it is actually rendering!!!!"

"SUCCESS?! Are you kidding me? And I didn't even break anything?"

Activity Viewer of the Manager/Server G4

Activity Viewer of the Server MacBook Pro
Have fun - I hope this works for you. I probably have needless steps in there, but give it a shot and experiment. I'll keep trying to figure it out. Anyone with more than 2 machines should try to see what kinks occur with multiple nodes. If you have a Mac network and got it rendering in no time, shame on you for not speaking up sooner and leaving it to an idiot like me to publish instructions that will probably crash everyone's machines. If you do crash following these instructions, I apologize - like I said, I have a knack for crashing and hanging computers.
CTRL-C is your friend.
kirk