Do like this: Make one partision and move the slider until it changes from xGB to xMB, then you know you've gone over the limit. Now go into advanced and lower the "End cyl" until it goes back to xGB, when it does that lower it 2 cyl more. now create a partision in the unused "above space limit" area. That done remove first partision and make the partisions as you like knowing you'll never go trough the 4GB barrier and when done partisioning remove the last "above space limit" one and you're done. To avoid issues with FFS reporting negative partision size you still have to avoid >2GB partision though.
