Do you know anybody that has the game on CD to install directly off of? I don't know of any way to tell the compressed download file to unpack to a different drive. (I haven't heard of a way, anyway).

Did you try copying the compressed file to your H: drive, and then double clicking it to unpack it? Maybe it would unpack to whatever drive it is stored on. (For example, if you've got it on C: and are trying to unpack it with the intent to install to H:, maybe move the compressed file to H: and start the unpacking/installation from there).

You may have already tried that... just brainstorming...