Great question! It's actually easier than you might think. AWD is awesome, but it's not some magic technology that allows you to defy the laws of physics. Given enough power, you can absolutely drift an AWD car, no problem.

When I first started experimenting with it, a lot of times I'd give it too much power and end up turning it sideways or doing a 180. It took a lot of practice, but I've got it down to a science. It's more difficult with fresh tires.

My year/make/model comes equipped with a button to turn off the automatic power distribution on the AWD. You can manually adjust the ratio with a little sliding knob. I haven't played with that too much, but you can change it to make it handle more like a RWD if that's your preference. I don't know if my year/make/model had a traction control option. Mine doesn't have any TC.

I also did some upgrades. I have a Cobb Performance Tuning Stage II chip, a Cobb high-flow exhaust manifold; upgraded DBA slotted rotors; HAWK racing pads, all-steel brake lines and am using DOT 3 high performance brake fluid. I fucking love my WRX. You get a LOT of car for the money, and there's a ton of after-market kit for it.

The Cobb chip comes with a device that you can use to remap the engine timing, etc via the ODBC port. You can download different profiles from Cobb based on the options you have installed, or build your own. I currently have mine mapped to high-performance to match my exhaust manifold. You can also map it for fuel economy, or go back to stock. It's really an awesome platform. It's an ugly car, but goddamn it's fast as hell, handles reasonably well, and is incredibly fun to drive. It's also tough as nails. You can really beat the piss out out of it.

TL;DR - AWD isn't a magic technology that makes a car impervious to drift. The Subaru WRX STI is an ugly car but absolutely badass. I love that machine.