NJkayaker,
From the PCA tech section :
The only proper way that Porsche has to disable the airbag is with the seat. What they actually use is a buckle that plugs into a receptacle. This receptacle is fastened to the front of the seat by the means of a solid bar. It is then plugged into the seat harness. Every time the buckle is latched into the receptacle it safely deactivates the airbag. You can tell that the airbag is deactivated do to the warning light flashes for one minute when the car is started or key turned is on. A dealer or shop with a System 2 tester has to reprogram the control unit upon this installation. At no time is it considered safe for a child to sit in the front until this has been done. An airbag can even blow with just the key in the ignition and the car not running.
Scott Slauson - PCA WebSite - 6/7/2004
Link
Hope this helps...
Nick