Themaister wrote some "hacky" wrappers around Genesis Plus GX, Visualboy Advance and Gambatte that route their APIs to match up with that of libsnes. That means any frontend for libsnes, such as Themaister's own SSNES, can now serve as a frontend for these excellent emulators. Thus, any features of the frontend, such as SSNES' real-time rewind and FFMPEG-powered video dumping capabilities, get baked in automatically. This also extends SSNES' badass GGPO-style netplay to all of these systems (where applicable, of course).
If you're using Ubuntu or another Debian-based distro, you can get precompiled binaries from my PPA repo. Other *nixes can compile them from source. The only dependencies are git (not even totally necessary if you manually download the source via http), a compiler that supports C++98 or higher (gcc-3.4 and up, IIRC) and zlib (in Debian-based distros, it's the zlib1g-dev package).
So, open a terminal and type:
For Genesis Plus GX:
git clone https://github.com/twinaphex/genesis-next
cd megadrive-next/src/libsnes
make
Download Windows libsnes-genesisplusgx binaries
(you may need to rename zlib.dll to libz-1.dll for it to work)
For Visualboy Advance (vba):
git clone git://github.com/Themaister/gba-next.git
cd trunk/platform/libsnes
make
For Gambatte:
git clone git://github.com/Themaister/gambatte-libsnes.git --branch libsnes
cd gambatte-libsnes/libgambatte/libsnes
make
For Final Burn Alpha (fba):
git clone git://github.com/twinaphex/fba-next-slim.git
cd fba-next-slim/src/burner/libsnes
make
Download Windows libsnes-fba binaries
The resulting libraries will all be called libsnes.so. In my packages, the libraries are named according to the emulator (libsnes-*.so) so you can have them all peacefully coexist.
One thing to be aware of: SSNES-Phoenix's file browser will filter out non-SNES extensions, so you'll have to manually type the filenames unless/until Themaister does anything about it.
Screenshots (dot-n-bloom shader is used for the GBC and GBA screenshots, CRT is used for Genesis and FBA):
