If you are still in school, it should be extremely easy: just approach a faculty member and offer to assist him/her. Most would welcome the free help. If you are out of school and want to do some serious research, I would imagine you'll need some funding. I'd think most grants go to PhDs backed up with an institution and with a good track record. Not having a PhD would make it difficult for you to be the PI. May be
@ptisfun2 can weigh in also.