Try getting your hands damp, lift her under the shoulders so she’s comfortably supported and stroke her belly. You may need to try a few different ways to pet her belly, but the point is to run your hands along her ungroomed parts while making her comfortable so it comes off on your damp hands.
Keep a waste basket or paper towel handy for you to wipe it off. It’s only a temporary solution, and you can graduate to a grooming glove if you want to try that.

Oh, and have a small treat or two handy so you can give her one as you start to handle her. She may put up with the manipulation if she’s distracted.

i always just put buttons in my lap and flipped him on his back. i only get a few seconds before he gets mad an flips himself over though. stinker. HAHA!