-
You can get textured plasticky stuff that's designed for inside showers and bathrooms. Usually clear. A strategically shaped piece of that would probably work better on top of a saddle than the abrasive stuff. Still grippy, but wouldn't rub through shorts/pad.
Edit: although it's intended for use on flat surface, so some creative use of a heat gun might be required to shape it to the saddle underneath, to avoid it peeling away from the contours.
Generic 'anti slip tape' from ebay, like this:
http://www.ebay.co.uk/itm/Anti-Slip-Tape-High-Grip-Adhesive-Backed-Non-Slip-Tape-/390433796352?var=&hash=item5ae7aaf100:m:mZ2UcWCb7AxFt3Unldyw4bQ
If you're tarty, make a template using masking tape or cardboard first, then use to cut the grip tape to shape.
Adhesive on skateboard tape is designed to be removed easily from a semi-porous surface, so won't adhere or resist sweat as effectively as the stuff designed for floors and stairs.