I know there are a couple of ways of doing this that have been suggested in the past including using a vbs that's about to script the runas command.

But while looking at deploying the latest OCS NG client they now have a tool to wrap this up and run it as a different user:

OCS Inventory NG Packager
http://ocsinventory.sourceforge.net/index.php?page=1-01

However in the install guide it also says that you can use this same method to launch any setup as a different users.

Could be handy to create a library of software that staff can install themself on their laptops etc...???

Ben