iPhone tethering to get around port blocking

Please dont take this as a personal attack, but as an IT manager with over 20 years in the business, Im betting that (if theyre smart) in addition to blocking the port, they have written policies about what you can and cant do on their network, including what equipment is allowed... I would.
Assuming you just want to get to your personal mail, if they allow it through, just live with whatever web portal your ISP provides and let IMAP sync when you get home on your own network.
I think youre asking for trouble trying to find a way around the system.
Though it might be possible to do what you want, its not really practical (this from a technical standpoint, not a policy standpoint). youll either need to tether your laptop to your iPhone and use the 3g connection, or use the company network. You cant really do both easily.
17" iMac Core2Duo Mac OS X (10.6.4) iPhone 3G, iPad WiFi 16GB

Well:
a. It is my laptop
b. I would not be using their network for downloading the imap data
c. I would not be downloading the data onto their computers
The policy is there to prevent imap downloading onto company computers, or more specifically through their network. As an unfortunate side-effect it prevents my computer from accessing imap email via the network. I am, however, allowed to hook up my lap top to the network.
I would not be doing anything on their network. This is not a question of how to bypass their port blocking using funky ssh tunnels or the like. The question is how to run two internet connections at the one time (if possible), using one for the bulk of internet traffic and the other for connections disallowed by the first.
The last paragraph of your response was useful and so I thank you for that. The 1st paragraph has nothing to do with what I am asking.
Macbook Air Rev C 2.13 SSD Mac OS X (10.5.7)