Downloaded and installed RC4 with the latest Max plugin.
Got an image to render with textures.
What I found is:
Maxwell Diffuse (old style like Beta, ah Beta) using a .bmp works in both 3ds Max and Studio RC4.
Maxwell Emitter or MXM emitter works in neither 3ds Max nor Maxwell Studio RC4.
MXM reflectance (with .bmp in the texture slot) does
not work in 3ds Max or Studio RC4.