Hi,
Only tunnel I have heard of is the tcp/ip tunnel protocol used for VPN encryption. It has nothing to do with "bypassing" any firewall, that would just bee silly.

Its more like that your IT guy can enable remote users to get into LAN/WAN via Internet using VPN tunnel.

I think its called pptp but I might be wrong.

To enable chat on the firewall, just call yuor boss, and tell him you have so much free time, you wich to be able to chat online, and ask him to tell the IT security to weaken your comppanys security by opening all fun ports on the firewall

But maybe there is some software that tunnels a point to point connection on a specific port, like the http port. For instance to remote controll an other PC.

If so, that will give the poor IT firewall guy a head ace But still wont enable you to use your pc at work for fun.

ps.
If you really like your work, dont ask. Someone might not think its funny.