First, you might want to go to http://admissions.caltech.edu/applying/transfer to see exactly which topics will be on the test. To study for it, the books you used at your community college should be good enough to get a reasonable grade on both the math and physics portions. However, you should spend more time then 2-3 weeks. A word of caution: if you do take the test and do well enough to get admitted, note that the transfer test's difficulty is not quite up to par with what freshman are studying over there. You might want to get the math books they use and study them over the summer before you arrive as a transfer; as they are quite a bit more advanced than what is covered at most community colleges. Caltech's single variable calculus, linear algebra, and multivariable calculus books are written by Tom M Apostol and can easily be found on amazon. Nevertheless, the books from your community college are fine for studying for the test.
Best of luck on the test man; I know you can do it.