Hi,
Instructions below ( You need Developer mode on star!)
Here is how to:
Add cruisecontrol / limiter to your Vito/Viano W639 it's configuration.
This should work for all W639 till AJ08
In Developer mode

tested version 10-2008)
In engine control unit:
Entwicklungen (Development data) ->F3
Password : flexecu ->F3
Steuergerate - Anpassungen (Control unit adaption) ->F3
Steuergerate-Anpassungen (Variantencoderierung) ->F3
VCD_Transporter->F3
a Pop-up tells you : "Mindest eine Codiereinstellung ist ungultig" confirm -> OK
Here you will find the option settings
write down the line that is blue.
For example : NSG or NAG_Klima_Wasserstandschalter
Now we search for the string that contains the same options + Tempomat and Begrenzer
So that will look like : NSG or NAG_Tempomat_v-Begrenzer_Klima_Wasserstandschalter
Once you find it , click it and confirm with ->F3
"Soll die Codierung in Steuergerat ubertragen werden ?"->F3
JA or YES->F2 to proceed
Now we log out the engine ecu and go to the :
Instrument Cluster ( Kombi instrument) (Magnetti Marelli)
Steuergerate-Anpassungen (Variantencoderierung) ->F3
Variantencoderierung Algemeine Daten->F3
Scroll down untill you see "Limiter" set to Ja or Yes ->F3
F2 -> F1 -> F1
Ansteuerungen -> Gesamstliste aller Ansteuerungen ->
Scroll down untill you see the line : Steuergeraet Resetten (PowerON-Modus) (FN_Reset_SG_Power_ON)
Press F3 and confirm again with F3
Now you will see the "Kombiinstrument" reboots
Cruise control coding is added succesfully to your W639 now
(THANKS TO QRIUS on DK for this INFO!)
Mark