Kitty litter isn't baked hot enough to act like Turface or fired clay products. I'm told it will eventually turn to Jell-O once kept wet. Or at least get soft and clump together. Do test some in water before adding it to a potting mix.
("Most of the people espousing the attributes of kitty litter are from Europe, where their litter is different than ours here in the US."
http://www.bonsainut.com/threa...
Also, most articles that I found suggesting kitty litter as a soil amendment add it to SANDY soil, not water-retaining potting mixes that need better aeration.)
If you can't get Perlite or coarse pumice to add to potting mix, consider crushed rock if you can screen that to remove dust, sand and gravel, but keep the grit. (Even "coarse" sand is too fine.)
If you know someone near a feed store or farm "co-op", "#2 chicken grit, crushed granite" is great for grit.
Or crush and screen some pine, fir or balsam bark, keeping the grit-size or BB-size shreds.
Maybe "aquarium gravel" would actually be fine enough to open up some potting mix?