Mohan - the major problem you're going to face, I think, is the slow performance of the permissions system, which dotLRN relies on heavily. I have done some experimenting with materializing views which dramatically increases performance but that won't be available until 4.7 is released in spring.
Just a heads up for you ...
AOLserver 4.0 (Tcl 8.4 in particular) should indeed help out Greenpeace a lot.