I made a post about this on another forum and got some good tips, but still with a couple of hiccups.
I want to be able to use projectile shotguns and new particle effects from AD in the base game and expansions. I've found a couple ways to do this, currently I am using QSS and have an AD_Id1 folder with all the files from AD copied into it, then all the maps/sounds/etc. extracted from the Id1 .pak files copied in as well (no overwrites so I keep the AD models and such). This works (and works for hipnotic and rogue as well) however, Shub is unkillable due to changes to his code in AD. Does anyone know what I'd need to edit or remove to fix this?