You basically install the Oblivion Mod Manager into the Nehrim/Data directory and use OBMM. The author updated the program to recognize either game. There's also a version of BOSS for Nehrim too. I'd go jump in the Nehrim threads over at SureAI to find out which mods are popular now. I'm over a month away from my game and don't really remember. Somebody else may have played more recently.