i personally use a very short glass slide (about 2 cm long) and i stick it on my middlefinger (!) like you would wear a ring, but not at the base of the finger but on the second joint. that way the tip of my finger is free to play normal runs and such but i can, at any point, switch over to use the slide. i maily use it in a jeff-beck kind of manner - i hardly every play those typical slide-cliche things for i simply HATE the sound of it.