I had a look at RedGreen,

I wrote that AnaBuilder is the only "real" software to build stereo photos. I mean that their exist other small softwares, but their features are so limited that they don't bring much more than few easy manipulations in a basic image tool..

For more stereo Mac tools, see in the "competitors" page of AnaBuilder's web site.

(And for RedGreen, it is not a freeware, but a shareware..)

Cheers.