I found the information a while ago... I'm currently running it as a service in Vista RC2...
I think that the major issue is that you can't install services unless you're logged into the administrator account. In order to access the administrator account, you have to enable it. I remember doing it throuhg Computer Management in the Administrative tools; however, I just looked it up online and couldn't find it.
However, once you've done that, you're good to go. The console will prompt you to set up the service and you'll be able to without a hitch.
Note that even if Vista says you have an Admin aco**** the "Administrator" account isn't enabled. But once you manage that, you're set
EDIT: I just looked into it further and think this would do it:
Control Panel --> Administrative Tools --> Computer Management.
Then go to "Local Users and Groups" on the left side. Click on the folder, that will branch out to "Users" and "Groups". Under "Users" there is an account called "Adminstrator".
Right Click, Properties, and remove the checkmark in "Account is Disabled"
Reboot, then you should have the option of loggin in as an admin.