You could use the runas-feature with them you could run a batch with another user and with the parameter savecred you could store the credentials: https://www.google.de/search?q=batch+runas+savecred
I see two possible problems with this strategy:
- You cannot lease a license from someone else except for the duration of the session-as-someone else. I don't know why you try to use Alternate Identity, but IMHO the lease will be gone as soon as the session ends. In QMC, you will have used one of the two possible MAC-address assignments though..It looks like you want to just throw away one license lease....
- When you load a document from the server, even in QlikView desktop, you will be an AccessPoint USER. And those are not allowed to reload documents. I guess this action will always fail.