I develop in both PHP and Java. Eclipse PDT appears to require DLTK 4.0, which it has no problem getting. ANTLR IDE appears to require DLTK3. I've tried copying the plugins 3.0 into my Eclipse plugins / features directory:
http://download.eclipse.org/technology/dltk/downloads/drops/R3.0/S-3.0.1-201108261011/
This worked on a machine without PDT, but I can't get it to work when I have PDT.
I have also tried using the marketplace, but I get the same dependency errors.
Note I'm on 64bit Linux.