I was able to enter the tomb of Ludo Kressh with party members also. The trick is : have your main character stand as close as possible to the area that triggers the dialog from Kreia about entering the tomb, then switch out your party members until one them is close to the tomb entrance. You'll probably need to switch them out multiple times before it will work. Use one of your party members to enter the tomb, not your main character or the glitch won't work.