Yea, if you don't have both of the originals it requires a trip to the dealer.
The following is from the manual...
Customer Key Programming
If you have two valid sentry keys, you can program new
sentry keys to the system by performing the following
1. Cut the additional Sentry Key Transponder blank(s) to
match the ignition switch lock cylinder key code.
2. Insert the first valid key into the ignition switch and
turn the ignition switch ON for at least 3 seconds but no
longer than 15 seconds. Turn the ignition switch OFF and
remove the first key.
3. Insert the second valid key and turn the ignition
switch ON within 15 seconds. After ten seconds, a chime
will sound and the Vehicle Security Alarm Indicator
Light will begin to flash. Turn the ignition switch OFF
and remove the second key.
4. Insert a blank Sentry Key into the ignition switch and
turn the ignition switch ON within 60 seconds. After 10
seconds, a single chime will sound and the Vehicle
Security Alarm Indicator Light will stop flashing, turn on
again for 3 seconds, and then turn off.
The new Sentry Key is programmed. The Keyless Entry
Transmitter will also be programmed during this procedure.
Repeat this procedure to program up to 8 keys. If you do
not have a programmed sentry key, contact your dealer
NOTE: If a programmed key is lost, see your dealer to
have all remaining keys erased from the systems
memory. This will prevent the lost key from starting your
vehicle. The remaining keys must then be reprogrammed.
All vehicle keys must be taken to the dealer at
the time of service to be reprogrammed.