Not really.
Since the issue is download speed, the solution requires downloading an update on another machine (and in the case of Safari, 6.1.3 for example, another machine, also running Lion, which hasn't had its version of Safari updated already).
I suppose copying the download from that other machine's /Library/Updates folder to a USB stick, then copying it to the same folder on his own machine, then running softwareupdate --install might work, but then again it might not...
