It has been a while since it last touched gentoo but it is quite motivated to check it out again. The only issue it has is that not all of its devices have enough power to regularly recompile everything and still be anywhere close to usable.
That's why it would like to setup a build server that does all the heavy lifting and hosts a binary cache with all the compleeted builds.
As long as the architecture matches between the systems it can just set up its own binhost, though it would require some effort to first build it on the server manually for the binpkgs to be preset. The API doc you found is for a system to automate that.
If the architectures differ it'll need to toy around with crossdev, which is underdocumented. navi has experience with it though, i'll poke her and see if she has anything to add to this.
