I can't get the plugins to work on both GMAX and Blender.
hmmm the Gmax one should have worked i got it stright from my max folder.
are u sure you put it in the right folder?
remember that the import is a script an the export is a plugin. thus need to be in the right folder (location in the readme).
AND that gmax plugins wont work for blender and viser verser
as for using them (if ur new to gmax). to use scripts -

then to export, click file/export then enter in this window -

i dont know about the blender one tho, i havnt used blender more then once.
ps give me some time ill find were i got my md3 blender from