You can not specify the location of a ClickOnce deployment. One of the major points of ClickOnce is to be able to install it with no admin privs. For this reason, it installs it under the user's profile in obfuscated folders. The folder structure is defined and determined by the ClickOnce technology, and updates won't work if it is not retained.
Maybe you should just use a setup & deployment package.
RobinS.
GoldMail.com