2012S3, you'll just have to keep the key (or chip) by the ignition where the antenna is built in. If I had a key, I like the idea of keeping it tucked in under the seat wired in series with DEcosse's keyless system; in which case you could immobilize the bike by removing the key. Alternatively I've heard of others getting around the key immobilizers by brazing the chip (the stem of the key) to the ignition barrel close to the antenna; although this would be less secure.
If I can add my 2 cents to DEcosse's design, it would be to use Transil type diode to shunt the relays. This supposedly saves the relay from some possible wear (http://relays.te.com/appnotes/app_pdfs/13c3264.pdf
);you'll note that Panasonic is actually discontinuing the parts with built-in diodes, possibly for this very reason.
Here is the part I intend to use:
Other than that, I'm just waiting on the parts from Eastern Beaver, and am psyched for putting the system together myself