Another good home-made-driver is to use duct tape. Doesn't that stuff work for just about everything!
No, really, once you have the seal in place you can wrap dict tape on the slider to a heigth that is comes close the the thickness of the seal but not quite. Leave a few mm's so that it will slide under the upper tube. You will then use the slider and ram and with a couple of well placed thrusts, the seal will be set in place . You then use a razor knife to cut the tape off of the slider (with care I might add), then use some carb cleaner or brake cleaner to clean off the residue left by the tape. Works like a charm and it doesn't cost much and it won't blemish the slider.