You have a few options:
1. He can sign in advance if all of the paperwork from title is prepared. Depends on how far in advance. If it is about a week away, you can probably pull it off, but if anything changes then he needs to resign whatever changed.
2. I have had one closing where the escrow/title company accepted digital signatures for closing, but my experience is that they REALLY want wet signatures on everything.
3. If he has access to a printer, then title can email what they need signed to him and he can wet sign them, get a notary locally if that is necessary (usually for the deed), and next day ship them back.
4. Limited Power of Attorney as previously stated.
Best option is probably #3. Good luck!