3DS MAX as compositing software

It is definitely possible, but a lot of work.
Lukas Lepikovsky built a "Quick Compositor" as part of his L Pass Manager script,
have a look at the video on this page http://www.lukashi.com/LPM.php
He demonstrates it at 1:01. It is not node-based though, but that could be done e.g. by using the helium framework http://lumonix.net/helium.html

I used a composite map and an alpha map to combine two renders inside 3dsmax once, so you can do some simple compositing without much hassle. But then I only did it because I was not allowed to use other software.