Here's another idea from my Honda head, buy the teg ign. switch with reciever for the immobby used at a salvage yard, also get the harness for the immobby
( I know a good place if you want the number pm me).
run the wiring for the immobby in your civic, it wouldn't be too bad just use your creative side....Take the switch to the dealership and replace it in the parking lot(or have them do it if your not at this level yet). and then tell the dealership you wish to get new keys made and that you did that swap. ask them to perform an all keys lost on the immobby and have a teg key cut for that ign. switch with a immobby key.

They will be able to make that new key work and in theory you would have immobby on your 99 civic. It wouldn't be on the gauges unless you were very talented and swapped that too but it would work in theory.

The above has not been tried by me yet, I know Honda/acura have like 5 different type of immobby systems. The newer ones are harder to bypass or mod. early ones were an ecu only deal, honda figured out the ecu swap and decided to make it harder and then the system used the reciever at the ign. switch. then so on and so on. let me find out the system that a 00 teg uses.