First. Throw away everything you know about 3ds Max immediately - Maya has a very different working paradigm - one that actually works rather than being bolted together bits of code that have been hacked repeatedly until they sort of half work but probably have been tested that well (a.k.a. 3DS max).
Maya and Max have nothing in common, and you need to realise that before you stomp through the Maya API expecting that it'll just work in the way you want it to. If you've not spent time learning lots (and i mean LOTS) about maya's hypergraph and DG, then go and do so now. These sort of operations should appear as nodes (Sure, you could go in stomping with your size nines, hack some MPxCommand together to make it do what you want, but it wont work. So don't try).
Take a very long hard look at the SDK polyModifer samples. They will tell you how to do everything you need to know. Your command should basically be something like:
n = get selected node
nmod = create custom modify node
mesh = create new mesh
attach n to nmod input
attach nmod output to mesh input.
Writing the node nmod may take a while.
p.s. Never ever use 3ds Max in the same sentance as Maya again. Max is a piece of sh*t. Put it in the bin and move onto more grown up toys ![]()