True, there are no special exceptions or 'bridge programs' for internals. There are several former rampers who I personally know that are now Captains though.
If you want this as a job while going to college consider this:
being a ramper, and a junior one at that, may be fun and have great benefits but it is a full time position. You can also be juniored to work on your days off if there is no coverage for open shifts. If you want to get days off by having others work for you it may be difficult depending on the station. If there is a lot of overtime, it will be hard. If not, then it will be a breeze.
While I was working side jobs at a DZ and ferrying, it was sometimes hard to get the time off I needed to fly. Good thing I was senior with a great shift or I would never have had Sat & Sun available to fly. The free flight benefits made me a great choice for a ferry pilot though!
While SWA is great with awesome benefits and flexability (usually), I can say that being a ramper really won't help you much in your flying career. However, if you have a good history with the company and are qualified later, you will get kudos for that. VP Jim Wimberly has known about my flying while working the ramp over the years and says he hopes to see me come back. Thank goodness I had an excellent record or I might have been totally out of a job when I got furloughed, but he was happy to have me back.
Do consider getting a GA type of job to help you develop the connections you will need to get time building jobs. Down the line that is what will really get you in the door at SWA or any place else!