I would say...first, make ABSOLUTELY SURE that it is for sure not safe to nurse on these meds. Alot of docs will just say that to cover their butts cause they aren't sure. Call an LC, they can find the latest info for you to help you find out, then if you decide to go ahead and continue, no need to mention to your doc unless some issue regarding it comes up.
With the night weaning, I used a method from the "No-Cry Sleep Solution" by Elizabeth Pantley. I would nurse him down like normal, and put him to bed in his crib. When he woke for a feeding, I would bring him to bed with us like normal, but only let him nurse for a very short period of time. Then if he started fussing for more/wasn't satisfied, I'd nurse again, but again for even a shorter time. After a while he just completely stopped waking cause he knew he wasn't REALLY going to get what he wanted. You have to remain somewhat awake and alert, but it doesn't take too terribly long. I kept a log of the wakings and the amount of nursing and you can see the improvement over time to help keep you motivated.