well there are several ways to do this. Just depends on what you really need. If the admin rights are for access to a file or folder, then you just need to change rights on that file/folder. If they are for making changes in the registry, if you know where, then you just grant them change access in the registry. Also, you can use a wrapper program using the functionallty of something like CPAU.exe from www.joeware.net
to launch the program with the credentials of another user. it's the same as a runas, but it allows you to script is into a file.
I use the following tools to do the above.
hope this helps you out...