How secure does it need to be? If they sell rackmount hardware, then there should be mounting points, it's just a matter of making up a bracket and buying some screws if you want a really solid mounting. I don't know if I would require especially sturdy mounting for a home lab, so a shelf as long as it can't slide super quickly (provided it's a slide-out shelf) would probably be fine alone if there were decent no-slip feet on the equipment. Wouldn't stand up to an earthquake, though, so maybe in some areas that woudn't do.
A strap would work too, if you perforated your rack shelf a couple of times, you could just use rope as well.