Hardwired my smartire system... (warning: many pics)
 

Thanks for the suggestions and advice skabaru and others. Worked exactly as planned.

I used Bryan's "easy way" to rig it. I just cut off the alligator clips and stripped the power adaptor ($3) and attached it to the Add-A-Circuit (what a marvelous invention, $7).
That's the main smarttire unit in the middle with the remote display on the right.
<img src="http://pictureposter.audiworld.com/20243/larryvs4-smartire2.jpg">

With the Add-A-circuit, you have the luxury of not having to find an empty spot on the fuse panel. I just had to figure out which ones were switched by accessory power and you can piggyback off another fuse since the unit itself uses a separate add-on fuse.
<img src="http://pictureposter.audiworld.com/20243/larryvs4-smartire3.jpg">

There's the main "brain" sensing unit stuck-on to the back of the fuse panel. I love zip-ties :)
<img src="http://pictureposter.audiworld.com/20243/larryvs4-smartire4.jpg">

I put the remote where everyone else had put it. I was trying to figure out a more creative location but this turns out to be the most practical and convenient. It sense air temperature inside each individual tire. Very cool.
<img src="http://pictureposter.audiworld.com/20243/larryvs4-smartire5.jpg">

And of course, the pressure for each tire is measured. A toggle button cycles through the four tires. The unit can be programmed to "sense" up to 20 tires... just in case I trade my audi in for a big rig some day ;)
<img src="http://pictureposter.audiworld.com/20243/larryvs4-smartire6.jpg">

I drove around for an hour today and the tire air temps ranged from 50 deg F cold to 80+ deg F driven hard. Surprisingly, the rear tires were always about 4-5 degrees warmer than the fronts. I wonder why? Bad alignment? Could it be due to my 19mm rear sway bar? any ideas?

All in all, very happy with the system. Peace of mind when running the 18's and potentially useful for the track. I got the smarttire system through edgeracing together with my wheel and tire package. Outstanding service from Max and Sacha.

Oh yeah... here's some new pics of my new shoes:
<img src="http://pictureposter.audiworld.com/20243/larryvs4-shoes08.jpg">
<img src="http://pictureposter.audiworld.com/20243/larryvs4-shoes11.jpg">
<img src="http://pictureposter.audiworld.com/20243/larryvs4-shoes13.jpg">

nice! those Kahn's are awesome on silver

sweeeeeeeet!!!

AWESOME! how does it sense the tire pressure? is there a sensor near the tires or something? Nice!

like this...
 

<img src="http://tirerack.com/tires/images/accessories/smartire_2nd_gen_bigger.jpg">
see those bands... each sensor is secured with the band inside the wheel (some wheels conveniently have little depressions for these bands to sit in). The sensors are motion-activated and shuts off automatically. Battery life is supposed to be 5 years during "normal use" (10-15K miles per year)

I just cut off the cigarette connector, added a fuse holder & went straight to the main ACC powe
 

<center><img src="http://ctny.audiworld.com/mark/s4/v1/dsc01306.jpg"></center><p><img src="http://ctny.audiworld.com/mark/s4/smartire/dsc02410.jpg">

neat! how much was the setup? sounds like it could pay for itself

Hmmmmmmmmmmmmm - I drive 40k+/yr, so my batteries may only last 1+ years :(

$220 for basic system... $50 for remote display...
 

definitely pays for itself by providing early warning and preventing permanent damage to just one tire during a low-pressure situation.

Tough to tell low-pressure visually with big wheels and low-profile tires.

Just curious -- since you had the kickpanel off, why not tap the 75x terminal instead
 

of using the piggbacks?

-T