Never tried Rom Collection browser but I assume it's setup similar to Advanced Emulator Launcher
When in first run setup
1) choose weather you want to scrape online or have assets locally
2) choose platform (let's say you'r setting up nes roms)
3)Path to nes emulator - browse to /storage/.kodi/addons/game.retroarch/addon.sh
4)Emulator parameters would be the coreID,launcherID,RomID ...I use fceumm "%rom%" for nes
5) path to nes is path to your roms folder
6)file mask is your roms extension ..for nes would be nes,zip
7)nes artwork just browse to your assets folder where you have your artwork or where you want the scraped artwork to be saved..
That should be it..