you will need to add a new target to the source. many of the retropie “modules” (emulators etc) for rpi2 platform will build specifically for the rpi gpu.
assuming ES works from Xorg on the cubieboard, you could look at the implementation of the x86 platform and work from that (you basically need a platform config that builds for arm – uses the default sdl1/sdl2 assuming that works, but doesn’t try to use mali or the broadcom gpu). the x86 dependencies are probably correct for you in this case.
this requires code changes to the retropie script.