Read this:
http://en.wikipedia.org/wiki/Automat...porting_System
Then go pass the test for a Tech class amateur radio license.
Then buy something like this:
http://www.byonics.com/microtrak/mt300.php (or the more powerful)
http://www.byonics.com/microtrak/mt8000.php
plus this:
http://www.sparkfun.com/commerce/pro...oducts_id=8936
And then just figure out a way to stuff the whole thing with a battery inside your seat post.