[JayG]

The delay relay boards could work. I guess its a little like reinventing the wheel
Here is teh same thing from a US seller
http://www.ebay.com/itm/DC-12V-Power-Supply-Adjustable-Trigger-Delay-Time-Relay-Module-Free-Shipping-/141733468250?hash=item20fff9185a:g:4GEAAOSwLVZVvJs W

As P-Wave said, you would need 2 of them and a 3rd plus an extra switch for service mode

Turning off the key is not a really great way to stop it in an emergency

the Autotop DIY costs maybe $15 and takes maybe 30 minutes to build and install
To stop or manually operate the top, you just press the existing switch

I forgot that Tom had bought the Robotop company
Robo-Top, One-Touch Convertible Top Module for 996 Cabriolets and 986 Boxsters, Convertible top module for Boxster and 911 Carrera!
Its $79 and a 1 minute install plug and play

the Autotop DIY is basically the same thing, just not as compact