Some form of D20 iteration of the monsters can be found via one of the SRDs. The Pathfinder SRD even updates fairly often.
Converting them is going to be an art, not a science. You can, from a D20 base, simply convert over the five stats that exist in both, then figure out a POW based on whether or not the critter needs it for its own purposes, has "Spell Resistance", or some other reason to have something other than a garden variety 3d6.
Armor can be mapped from any "Natural Armor" bonus the D20 version has. Not necessarily 1-to-1 or even a linear relationship...
There are enough examples in RQM to map natural attack forms reasonably well.
Supernatural and Spell-like abilities should probably start from the RQM spell lists, but RQ has a long history of monsters with "w'the heck?" abilities, so be prepared to make stuff up.