umm, if you cannot take the cage out, maybe you can take out all the substrate, then spray PAM on it when it is far away from your animals, maybe do it outside if the weather permits, and return it after it has fully dried, and clean out the cage while the treated substrate is drying up.

that could work. i mean, it avoids the risks, but i wonder if it would be as effective. but then, its supposed to stay active in the substrate for 30 days, so i suspect it would work.