I recently got my car serviced at Klosters Hyundai in Hamilton, Newcastle and asked the sales staff about retrofitting the cruise control onto my 07 slx crdi. The guy there said they CAN do it but its not cheap [i think he said 700-800 fitted]. I asked whether it is a stalk or aftermarket looking kit and he said no, it is the same as the factory cruise with the buttons on the steering wheel like OEM but as they cant have the cruise activated/deactivated light on the speedo, supposedly there is an led that is mounted on the plastic trim to show when the cruise is activated or deactivated.
If you want to contact him, his name is Simon Drummond ph: 0422 514 182, email simon . drummond @ klosters . com . au [remember to take out the spaces] and this is at Klosters Hyundai in Hamilton, Newcastle, Australia.