I can't advise on the EHR changes that would be required (my colleagues at Galen definitely could), but I can think of some things that would need to be changed in ConnectR:
1. ODBC connections
2. Any mapping scripts that reference ODBC connections
3. Most system definitions would need to have their communication settings re-configured; definitely the TCP/IP connections.
I'm sure there are more!
If you need help, let us know!