Katarina can jungle?

Sorry without the proper runes, it's hardly possible (even with them) The, main reason is her early AoE damage is garbage and cannot sustain unless you're going AD Katarina. I assume that you would need to carry a lot of spell-vamp @ level 1, so your level 2 clear can sustain you to around level six. Her base items would be Spectral Wraith and Will of the Ancients, which would cause roughly 1100 AP damage. Statswise, Katarina has a higher AD ratio on her Ult than the AP ratio, so if you can pull off an AD Kat you'll need some lifesteal.

Virtually every champion can jungle, although not many can do it without runes.

I really don't see any reason why you'd ever want Katarina in the jungle, tho. Her ganks an objective control are nonexistent, and her kit doesn't really allow her to function in a low-econ role like Jungle.

^^^ Is this possible? If so how? (masteries and item path only please, too poor for runes so far XD)

It's possible. You can jungle with anyone if you have enough fighting spirit.

You just won't clear as fast and gank as well as most of the top-end junglers when you do things like jungle Sivir or jungle Janna, which is problematic when you're matched against opponents that will take a mile if you give them an inch.

If you're asking the question - you probably aren't matched against those people though, so run Kat jungle in a few Co-Op games to get a feel for it and see if you like it. If you can get a decent pattern down, being anti-meta and making it work is really entertaining, and can be pretty inspirational.