Someone posted some source files on integrating multiple interpolation formats into bsnes-mercury - none, linear, gaussian, cubic, 8-tap. Seems simple enough?
gaussian.cpp, fir_lut.h, snes_options.txt http://s000.tinyupload.com/index.php?file_id=96393311565236981421
Binary posted elsewhere uses some weird dll run-time injection method into bsnes-mercury so not posting that here; seems like odd idea to make it work.
I suppose it would be simple to also modify for snes9x-next, given they’re both blargg’s library.
Just mentioning this though. Kinda interesting listening to raw vs snes vs “hq” interpolation.