Step 1. Make sure the SOCKS tunnel on your work computer allows LAN connections so your iPhone/iPod Touch can connect to it.
ssh -N -g -D 1080 user@domain.com
Step 2. Create a text file and insert the following code:
function FindProxyForURL(url, host)
{
return "SOCKS 192.168.xx.xx:yyyy";
}
Replace the x's with your IP and the y's with the port you used after the -D in your SSH command
Step 3. Save the text file as a Proxy Auto-Config (PAC) file to a web accessible place with a .pac extension.
If you're reading this chances are you know how to serve a file over HTTP on your work LAN, so I won't delve into that.
Step 4. Finally, on your iPhone/iPod Touch, go to Settings>Wifi and click the blue arrow to the right of your work network. Scroll to the bottom, click Auto and type in the address to your PAC file (e.g. http://192.168.xx.xx/mysupersecretproxy.pac).