Variables in control file

Hi all, I would like to know how to use (system) variables in the control file - I need to use the asset tag of the systems as the system hostname, and it is not immediatly obvious from the docs and examples how to do this. I have a one-line shell script that uses hwinfo to get the asset tag, but I am not sure how to get this into the control file. I am using suse9.1 on the clients and sles9 on the server. I tried searching on google, and the archives, but no luck. Any help would be appreciated. Cheers, Martijn