If you have the Retail/OEM version, it should already be able to install any edition of Vista. The installer will automatically select the correct edition based on the license key. If you have the VL (volume licensing) version, that's different media, and, as far as I know, doesn't support such operations.
If you do, indeed, have an edition-specific version (which shouldn't be possible, since only 2 DVD types were made for each architecture), then you might try those instructions. The setup and servicing stacks for Windows 7 are the same ones used in Vista, so all of the dism commands should be the same, but the media format is quite different, so there's not a terribly good chance that those commands will actually be valid on the media or that it's even possible. (Without going into details, offline servicing was changed quite a bit for Windows 7.)