I spoke with the director of admissons at UT, and he informed me that the AMCAS online application would be undergoing some changes for next year's format (applying for Fall 2006). It was not yet available when I checked a few weeks ago, and I was told it would not be until earaly in the year (2005). One thing you may want to do is put together a list of your classes taken, grade received, hours received, course number, course classification, AMCAS code, year taken and the school at which it was taken. Each class will need to be manually entered into the AMCAS application (the only reason I know was I got confused when last year's was titled AMCAS 2005 and I filled it out). Also, you should probably start requesting that you teachers prepare recommendations for you.
Good luck, hope this helps!
Adam