I dont think you can turn Viconia actually good ? You can turn Sarevok chaotic good, but the best you can do with Viconia is AFAIK true neutral. Also I think you have to romance her to archieve the later and I never did that, because she would leave the party once reputation crossed beyond 18.
I never figured out how to play BG2 properly as evil, or even neutral. My reputation always shot up to 20 very quickly. Murdering random innocents could bring it down but that was no fun at all.
