This is much like repairing your bicycle's inner tube:
Clean the area of dust. Cut a patch from bellows cloth or soft
leather. Apply rubber cement to the patch and to the area to be
repaired, going a little beyond the size of patch. After the
cement sets up (about 10-15 minutes), carefully position and apply.
It grabs immediately! Rub down the patch. Gently. Dust liberally
with baby powder.
This is easy and it's permanent. It does not take the place of a
bellows recovering, but its close.