Help, I removed the accumulater cover when I installed a B&M shift improver kit. I don't think I got the o-ring in right. Does it fit around the cover or just sit in the case against the lip inside?:

Always stretch the o-ring a little, then position it in the case--not on the accumulator cover. Grease liberally and push cover in place. If the accumulator spring is still installed, keep steady pressure while you snap the retainer ring into place. If no spring, the cover will stay put with no extra help. When properly installed you should be able to push in on the cover and see it move back & forth about 1/16" or so with no binding.
Mike

P.S. Went back & re-read your post. As to your original question, the o-ring sits against the small lip inside the case. Then follow instructions above.

Thanks, Thats how I installed it. Hope to have it running next week & I'll find out then if I did it right.