Evolution of a feline humanoid, specifically upright walking and fingers

Question

I would like a realistic evolutionary path for non-hominid humanoids, but evolution is extremely complex and varied, so I will narrow the question to examining how evolution might occur in felines to produce a humanoid. I would like to start with the Pseudaelurus (a prehistoric cat) and move to an upright walking, fingered and toed omnivore (cat's are obligate, "true", carnivores). I think I have a reasonable idea for how to evolve their diet (included below for reference), but I'm stuck trying to come up with a reason for hominid like fingers and toes and upright walking. My question is, what types of environmental/cultural/etc... changes could lead to a feline developing upright walking and hands capable of hominid like grasping?

Evolution of Diet: Assuming the cats were native to a plains environment with ample hunting opportunities, an environmental shift (ocean's rising, tectonics, something else) could force the felines into a wooded environment with a much smaller number of prey. This would lead to adaptations for including fruits and other forest products into their diets. It would most likely also favor tree climbing adaptations like those seen in leopards.

Answer 1

Moving to trees and/or a rocky area would help. Hands and an upright posture are good for reaching and carrying things. They are also good at manipulating things and tool use. An upright posture is also good for spotting predators.

What if the cats were driven out of the planes by larger predators and there where small wooded areas where small critters lived in the nooks and crannies of trees with deep bark ridges. The cats need to reach in and around to reach the prey. Eventually they would use sticks or hooks to grab prey and maybe tools to widen the holes.

They would have to cross the planes to reach new food sources. Being able to see over the tall grass while they moved would help avoid the predators. At first they would move and pop up to peek then move again. The longer they could look while walking, the better their survival chance.

Eventually they develop tools/weapons to help defend themselves against the larger predators. Then they use the weapons to drive of rivals since, without the predators, their population rises past the point the prey can support it.

Answer 2

As far as I know the only large animals with grasping hands/paws are those that live in (or used to live in) trees. And reverse, the tree dwelling animals that I can think of off the top of my head are either flying, have grasping hands, or are small enough that they can use sticky feet (insects). Well except snakes that is. So the scientifically safest way might be to duplicate hominid evolution: have the felines move to the trees. I don't know what the scientific consensus is for why humans started to walk upright but if there is one you could probably adapt it too.

If the felines are still obligatory carnivore they wouldn't have started living in trees without food there, so either they already started eating fruits or there are other tree dwelling animals that they could hunt. At the same time on the ground there are larger predators that would eat the felines if they could.

Answer 3

Theoretically, sometime between when our fishy ancestors crawled out of the ocean and the first recognizable primate swung from a tree branch, there had to be something that walked on four legs ending in paws and claws. Curiously, there's almost no data in an (admittedly rapid) Internet search that theorizes that happened before the chimp. Probably because there isn't any evidence of one species evolving into another species. But that's not really the focus of your question, anyway.

Therefore, I'm a fan of @ShadoCat's answer (and I upvoted it) because he's describing perfectly sensible adaptation. Paws elongate and rotate on the "wrist" to become "hands". The cats stand up as they need their hands for something more valuable than running. Etc.