Hi Juan,
From SW in the part file, I added the "denim" material (it comes with SW)to the entire body (just as a test). Though I could see it in SW, it had no effect in M~R.
Near as I can tell, in SW, you can not assign to which "channel" the texture applies. I assumed

that it was applied to all of them, and from the M~R material MAPS you select which one you want the texture to be applied to. This didn't appear to work.
I have never liked the way that SW handles color/textures. In the past (I haven't tried this with SW2006 yet), you could apply a color in a sldprt file. But if you change the color in an assembly, the assembly color has priority. This has had bad consequences for me in the past. Now, I apply color in the sldprt only, and do nothing to it in an assembly.
I feel for you working with SW in this regards. Though I love SW, the way things like this are handled is not very good.
Might I make a suggestion for the SW Material Editor? I like the way that it is handled now. But I would like to see a more "linear" approach in that you create the name, then underneath you set your next attribute, onto the next until you come to the "end", at whcih point you click "write". If you want to change a material after that, you just "go down the list" and hit write again.
One other thing; if at all possible, overwriting the SW color on the screen; if I have a "blue" sldprt, and my M~R material is "green", the window does not update the part with the new color. This is probably a SW problem, and I understand if you do not have the control to change this. A "material preview window...?
Also, do M~R materials get "attached" to the sldprt file itself? If I have a part that has been assigned m~R materials, and bring it into anassembly, do the M~R materials "come with it" or do I have to assign them all in an assembly?
All in all, I am thrilled with the prospect of where this is going with SW/M~R. If we only could do animations (light intensity envelopes and such) from within SW, it would be incredible...
Thanks very much!
Mike Tripoli