Darn, didn't work so well for me and I also followed the procedure of ~ 4-5 min with soaking in Isopropyl. I have the cloth liner, I got my car in November 06.
The problem is around the corners and some edges that has the blank line. The decal didn't come off easily in that area. In retrospect, maybe had I soaked longer, it would have worked better. I continued to work at it, but there are still black lines left that don't seem to come off.
Note, I am not entirely sure that the black adhesive has stained the cloth, although in some spots appears that way, it could also be that the adhesive is very fine particles and simply embedded into the cloth. I tried pushing scotch tape down against it though and couldn't remove anything. I feel like I'm out of options.
Does anyone have any other ideas before I give up?