There are plastic stick on films, we call them footballs that can be placed between the lens and the leap pad on the front and also on the back side of the lens to prevent slipping whlle edging, also most pad companies are coming out with leap pads especially made for hydrophobic coated lenses. P.S, don't wipe then lens clean before blocking , it removes the surface tension on the ar coating. clean it well after edging.
I've edged,drilled and tinted quite a bit of Trivex. A bit hard on the edger wheels, (keep them clean.) I use the ACR (acrylic) setting or some edgers have the TRX setting. It polishes nicely. Also drilling is very nice. The tinting is faster and color comes out truer, more like uncoated cr39 than poly or hi index. good luck