[benji]

Masking tape can hide leaks and won't stop a river of dye. Use a brush to cut in around edges, or those make up applicators - little foam buds from the chemist. You can tidy up the glue that will be on top of upper in places, either with a little careful acetone, or if you are dying them black then sharpie over the glue after dying. The dye won't penetrate where there is glue on the upper. Good Luck.