The normal way that's done is with a radio that has mutiple model memory, of course.

I have seen some speed controls advertized with the feature you are looking for, but if your's doesn't have it, you are out of luck, you can't just switch wires around. If you think about it, you can swtich the output wires around to make the motor run backwards, but low is still low and high is still high. The signal wires coming in to the ESC (or a servo) aren't reverseable.