This is an old thread but since the topic comes up so much, I'm happy to weigh in on it here. Taking additional graded coursework is a good idea, but I'm not sure I'd see that as an "alternative transcript", since it doesn't blot out any earlier sins, but more like an additional piece of crucial information about your academic capabilities, maturity and commitment. Definitely take highly reputable courses, such as the UCLA Anderson or Haas extension courses, which have demands and give grades. But do this in a systematic way, ideally after you have an idea of your strengths and weaknesses regarding the GMAT. Do you have a mediocre Q in the GMAT and not enough quant coursework in undergrad? Take the courses you will need to build up that capacity -- core stuff like calc and stats. Do you have strong Q but low Verbal? Work on business writing courses. Are you making a transition from software engineering to management? Try Harvard's HBX CORe, a full program that is specifically designed for this purpose.

Again, it will definitely add value that you get 4.0 in these classes, but it won't efface four years of partying in undergrad, so an optional essay will be in your future. One last point here: PLAN AHEAD. As the original poster noted, these courses fill up fast, so deciding to enroll in June when you're applying in September may leave you out in the cold. Best to work on this starting a year before your deadlines.

Good luck!
Margaret Strother