2004 Elantra GT - third remote and key problem

I recently purchased a 2004 Elantra GT 5 door hatchback. When requesting
a third key and remote the dealer here in Montreal tells me they cannot
supply a third remote because the car's computer is only programmed to
accept 2 remotes. He says he can disable the alarm system, which would
then allow me to open the doors with a third key which they can supply.
Has anyone else had this problem and found another solution where a
third remote can be used. I do not want to go to a third party remote
starter system for the car.

 

This car will only recognize two remotes. The alarm will only set if the
car is locked with the remote.

 

The hyundaitech entity posted thusly:

I have a 2004 Elantra, and this little "feature" is a real bother. I
recently purchased a remote starter, and because the alarm is
set/unset only with the remote, it means that I must use two remotes
(the AutoStart one and the Hyundai one, if I want both remote starting
and an alarm.

Does anyone know if someone has figured out how to set/unset the alarm
without the remote? I have a few available outputs on the remote
starting unit, and if I knew where to wire them in, I might just go
for it.