SSO

Hello everyone, i am new to this forum and to WordPress all together so I hope this question is not all that redundant.

The Master site will be my WordPress site but i will be using Invision Power Board for the forums. So for users to be able to cross over easily i figured i would need to enable something like SSO, but the sad part is i have no idea how or even where to start.

I have found a few plugins regarding this but it is all referring to invision power board being the master and WP being the slave site.

Any help would help me out alot and even if you point me in the direction of a guide, i would enjoy that as well.