Yes, SourceAnywhere for VSS Visual Studio IDE
Client supports working in disconnected mode.
To work disconnected, you can go to File | Source
Control | Change Source Control and click Disconnect.
When the network becomes available, you can
connect Connect in the Change Source Control dialog box.
Click Continue to check out the file.
You'll get the following dialog box if you made
any changes when offline. (Make sure you set Replace writable files setting to Ask at Tools | Options| Plug-in Settings | Advanced button). Choose "Leave this file" to keep your offline changes.
Then you can perform Check In to commit the
offline modifications to SourceSafe database.