Of course, you can climb Mt. Baker car to summit in one day, but if a guy is traveling all the way from Mississippi, I assume he wants to learn mountaineering techniques as opposed to just getting up to the summit. And 3 days is not that long compared to the wealth of things out there to be learned and practiced: glacier/mountain camping, knots, prussiking, climbing and descending snow slopes, cramponing, ice ax self-arrest, snow anchors, roped travel and crevasse rescue at the bare minimum. Then there's also route finding, map&compass navigation, and judgment which are skills that you gain with experience.
So my point is, know whether you just want to climb Mt Baker or to learn mountaineering. Then look for a guide/guiding company that will give you what you want. As of AAI, I took their 13-day training course and they were absolutely awesome. Oh, and one more piece of advice. Before you sign up for anything like that, go on a lot of uphill hikes. That will help you develop musculature and get you used to climbing. Being adequately strong will make sure you get most out of your climb and the climb will be enjoyable. I've seen too many newbies out there who despite being in pretty reasonable shape dreaded the climb just because they had no musculature for intense uphill climbing.