How to convert voltage?

[murdoc]

Ok I know there are a few electrical wizards on this board so here goes.  I want to hard wire my garage door opener into my car.  The car's electrical system is 12 volts.  The garage door opener works off of two 3 volt batteries (the thin watch type).  Does this mean the garage door opener needs 6 volts?  Next, how can I get the voltage to drop?  Space is going to be a premium.  I plan on mounting the opener inside the dashboard and using a remote switch to activate it.  This is pretty much what I'm looking to do: http://www.vb.quik.com/jmciver/pages/garage.htm  The guy that created the website however, was using a 12 volt opener.  I cannot change to a different opener without changing the entire setup.  Any ideas?

[waterhead]

Maybe you could use something like this:
http://www.powerstream.com/dc6.htm

[Doug Mohr]

Radio Shack sells adjustable DC voltage reducers. Gutting one and hardwiring it will be easier than building a voltage reducer.