If you find or manage to create a good walk cycle, you can save it as a pose file into the Walk Designer folder, then access it from the Walk Designer panel the next time you launch Poser. Make sure you turn off IK on the front limbs.

And no, I don't know of any free walk cycles for the cat. Horses, yes, and even the dog, but not the cat. Although I'll admit that the dog's walk-cycle doesn't look bad on the cat, after some adjustment. Unfortunately, it's by Debbie and I don't know where you can find it any more.

Credo sells several animation collections for the Poser animals, including the cat.