Either way you're ruining the leather, which hurts. Personally I wouldn't be able to do that to good leather. However ...
The problem is complex. Normally leather glue would do it, but most leather glue will not adhere patches, because most new patches have a plastic backing film that won't adhere with it. If your patches are all vintage, Fabri-Tak would work, because it will bond fabric to leather, but if you have that shiny plastic backing on the patches, it won't work. Leather to plastic is a tough problem.
The best glue I know of that will work on leather and on *most* flexible plastics is Polyvinyl Acetate, known as PVA. Unfortunately it is also water-soluble, which means that the first time the jacket gets caught in the rain, the patches will loosen.
What I would suggest you do is to ask at a shoe repair shop. They use specialty glues that are specifically made for leather and plastic, and would know if there is one out there that will properly handle both of them and resist water.
You could also sew on the patches using a curved upholsterers needle to only go through the leather (which is the right way to sew it, anyway; sewing clear through the lining and the leather would cause the jacket to fit badly because the lining would no longer move independently). Be sure to allow a LOT of time for doing this, get a good thimble and hope that you have strong fingers; you'll have to push VERY hard to get through both the leather and the sizing used to stiffen the patches, and that's tricky with a curved needle. It helps to use a rubber-tipped needle-nose pliers to pull the needle through from the sharp end.