for snes (with snes9x):
unzip all the rom and remame for xxx.smc. now right click with your mouse on one rom and select open with, find the emulator and select the "always execute with this app", the emulator launch the game exit the emulator and go to xlobby make your database, now when your clicking the rom in xlobby is opened with the emulator (make the emulator open roms in fullscreen)
for genesis/megadrive (with gens):
unzip all the rom and remame for xxx.gen.Make a batch file with this line
cd C:\Program Files\Media Center\Consolas\Megadrive\EMULADOR\
gens.exe %1
make sure the path of gens.exe corresponding with the location of your emulator gens directory.now right click with your mouse on one rom and select open with, find the BATCH FILE and select the "always execute with this app",the emulator is launched in fullscreen exit go to xlobby make your database, now when your clicking the rom in xlobby is opened with the emulator
for the NAME and the N64 it's more dificulte because on name the roms it's only zip or rar file and the N64 emulator don't launch the roms directly from the rom only with the database manager included in the emulator.
this is the only help i can offer you MEGADRIVE and SNES