It can be done, SAGE engine is nice like that. And by the looks of it, it looks like it takes some graphical stuff from C&C 4 as well. I could be wrong though.
Kind of late update for this, but here's some late promo images for end of MOTY 2014, voing for this mod would be highly appreciated, you can do it on mod's main page
The tripods use shader from C&C 3, in RA3 mod?
It can be done, SAGE engine is nice like that. And by the looks of it, it looks like it takes some graphical stuff from C&C 4 as well. I could be wrong though.
ra3shaders
As far as I know both ra3 and C&C4; are using the same engine and the only small different is some new shaders and codes