More fun with mac scripting. There's a way to connect to a share on the network (mount/connect to a server if you're hopelessly lost in Mac-only parlance) using AppleScript:
tell application "Finder"
mount volume "smb://myserver.mydomain.net/myshare"
In my test, this code completed successfully, so it communicates with the Key Chain properly and finds the correct user and everything. It's rather impressive that you can coax so much functionality out of so few lines of code. What can I say? I'm becoming a fan of AppleScript.