I really like IndyWave's approach, but I took the more traditional looking tiller route.

Basically mimics the setup of that on a Getaway, but at a fraction of the cost.

I have been sailing with my 'home-made' tiller for a few weeks now, and I can safely say it is worth the effort. I love having the ability to sit in different locations, ie farther foward when running, or light air sailing. One comment I will add, when sailing in really wild wind conditions, say where you are sitting pretty much under the tiller to keep the bows up, then you may opt to strap the tiller ext in place and just use the tiller as it was intended.
But my concerns about 'stress' on the crossbar seem to be unfounded. It works out great. The only issue I have is when the rudders are raised, the tiller extension must be flopped off towards the stern, ball lock bungeed as was suggested, or left to rest on the rudder housing. If not, the hinge tends to bind only slightly on the crossbar causing some minor scratching. This is due to the extreme difference between the up vs down postion of the crossbar.
Not a biggie though.

I began by mounting my crossbar upside down, see the pic, brought the rudders down, and postioned and drilled the hole for the hinge 5 to 10 degrees forward.

Again, here is a materials list for those who wish to try:
Hobie standard hinge p/n 10532010
yoke p/n 3205 ($16 for these two parts)
soft grip 3206 (from page 23 of cat, fits perfectly on the 1/2"cpvc)
(if you want to save the $9 of this Hobie grip, then opt for a 30cent CPVC cap <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" /> )
60" length of 1/2" cpvc (I bought mine at Lowe's for less than $2) leave it at this length,
3' or 4' length of 1/2" wood dowel (sanded slightly, and pounded into pvc to stiffen)
a little urathane glue like 'marine' Goo to glue on the grip.

Here it is with rudders up

And rudders down while underway...