I've checked and it appears that you can install Inpaint directly from the Software Informer client, even if you have another hard disk.
To do so, download and install Software Informer client then start it and simply type Inpaint in the search box. It will appear in the list. Click it and the download should start.
Note: If you have a firewall, add Software Informer client to the exclusion list to be able to connect to the Internet and download the installer file.