100% MR in BG2

I was wondering if it is possible to get to 100% Magic Resistance by the time I get to BG2. It's always something I wanted to try but it's been years before I gave it a shot. Can anyone tell me if it's possible with a thief with UAI. I'd rather do it without Carsomyr. I was also thinking of taking a Wizard Slayer through BGEE to Thief to get an extra 15% MR or so if I can't get to 100% with only items.

Also, has anyone actually done this? How useful is it? I picture my 100% MR to allow me to brush of liches and Fire Giants. Is that actually the case?

Thanks!