Ok, here's the deal...
Getting a pilot slot "off the street" is difficult but not rare. I was offered 4 slots when I was applying and I was just fresh college grad and new CFI. Several other friends got accpeted for pilot training. It helps if you're enlisted in the unit you're applying to, but why lock yourself into something you don't want? Do not enlist, stay persistent. Most of the pilots in the unit weren't enlisted to begin with anyway.
Your first step is to call as many guard units as possible. Go to the ANG website directory and get the info. I thnk Air Inc. puts out a directory of units as well. Speak to the personnel office and ask when they're haveing a UPT (undergraduate pilot training board). Ask what they want in their application package. Most require: cover letter, college transcripts, resume, letters of recommendation, copies of pilot certificates, and AFOQT scores (air force officer test like the SATs). They can give you info on where to take these tests.
They will have a group of officers usually pilots go over the packaegs and pick about 10-15 people to interview. Most of the time a unit will have 2 slots pick for. The interview is just their chance to see if you will make a good officer and someone who they can drink some beers with.
Things are a little different post 9/11 but there are still opputunities out there. Good hunting.