Yes it is possible to add them you need OpenIV for example if your uppr is uppr_diff_000_a_uni you must add the files like 001 instead of 000 and do this on every file in that archive after that rebuild the archive you must rebuild it to prevent from crashes and you are set go in game and play.
My PC Specs:
Intel(R) Core (TM) i5-2400 CPU @ 3.10GHz 3.40GHz
RAM: 8 GB
GFX: Nvidia GT 440
OS: Windows 7 32 bit