Career changer programs vary in their admissions requirements. They include the formal postbacc programs like Goucher and Bryn Mawr, which are commonly considered to among the top programs of this type. They commonly have a relatively small number of slots per class (30 at Goucher, 80 at Bryn Mawr), for which they receive hundreds of applications a year.
With a large number of applications to consider, numbers like the GPA and test scores start to become a valuable way to sift through the stack.
In addition to being competitive simply on the basis of the number of applicants per seat in the class, the formal postbacc programs also want to maintain high statistics regarding their graduates' admission to and performance in med school. Those high stats both attract new applicants and ensure adcoms have a positive view of students who graduated from said program (thus improving future students' chances of admission). For this reason, the formal postbaccs are looking for students who have demonstrated an ability to perform well in the academic arena and evidence they test well on standardized exams. That gives the postbacc program some kind of assurance that they will turn out students who are likely to reflect well on the program during the application cycle and into their medical careers.
At a complete guess, you probably want a GPA >3.5. It has honestly been so long since I took the SAT that I don't understand how they score the thing anymore, so I'm not going to venture an estimate on that. 🙂
There are less formal career changer postbaccs that are probably still looking for fairly good stats but are less stringent. That could include the Harvard Extension School, Tufts, etc. Once you start looking, you'll find a ton of programs in this category. They vary in things like support to the students, but many of them have a long track record of getting career changers into med school.
Finally there are the do-it-yourself programs that likely vary with regards what stats are required, if any.
There are a number of good resources in the FAQ section at the top of this forum. Good luck!