Another PS3 proxy utility, this one by 3r1c and additional info is in this thread:
This one is much more easy to use then the CF3B5 version and has some extra functions.
* Written in English.
* No need for reconfigure your PC's IP addresses. The program shows you the IP you need to use
* No need for installation just run it from anywhere.
* No need to download pkg files to your pc, the proxy will redirect the ps3 download to the url you enter.
* No need to download 1% and then cancel, the proxy will intercept the download automatically.
Using this program is simple.
Just run it, set the proxy port or leave it at 8080.
Press "Start" button.
The program then gives you the IP and port you need to configure in the PS3 network settings.
Then you just click the browse button to select the pkg from your hard drive, you can also choose to enter an URL.
Tested and working with GripShift.