To my knowledge there is no way to do this. I have a solution however. First of all, avi's from Maya are horrible according to the pro's. It is much better to render out in targa (the best format I believe) then convert those images to avi using a program. VideoMach can take a sequence of images like this, then make them into an AVI (or another video format like MPEG if you prefer).
Here's the punch line. In VideoMach, you can change the frame rate to as low as 15fps or as fast as 60fps easily. VideoMach is a free download and can be located at download.com. So by doing all this, you can change the frame rate *and* create a higher quality animation.
And I couldn't post any of this without giving thanks to mtmckinley since he was the one who told me about VideoMach several months ago. Thanks bud.