the Materials Collection was introduced when the render-er changed in 2007.
Materials in 2006 and earlier are defined by the old ACAD_RENDER ads program and are not accessible via activex - I don't know if there is even a command line version for attaching materials to a layer.
These are the only commands defined by the ACAD_RENDER arx:
c:3dsin, c:3dsin
c:3dsout, c:3dsout
c:background, c:background
c:finish, c:finish
c:fog, c:fog
c:light, c:light
c:lsedit, c:lsedit
c:lslib, c:lslib
c:lsnew, c:lsnew
c:matlib, c:matlib
c:render, c:render
c:renderupdate, c:renderupdate
c:rendscr, c:rendscr
c:replay, c:replay
c:rfileopt, c:rfileopt
c:rmat, c:rmat
c:rpref, c:rpref
c:saveimg, c:saveimg
c:scene, c:scene
c:setuv, c:setuv
c:showmat, c:showmat
c:stats, c:stats