With LinkSys the default address for the router (via the WebInterface) is
http://192.168.1.1 open this address in your browser.
Your default password is Admin, the name nada matters.
Click on the Status Link that comes up (a psuedo Tabbed-Dialog) and get your actual IP address. This might change if you power the LinkSys off and happen to hit a lease expiration. I've kept my address for over 1.5 years, even though it's dynamic.
Decide on a port for MJ (don't use the default of 80 - we're gonna intercept all port traffic coming in and send to your machine. If you use 80 no one else on your network will get web pages.) 8931 as the MJ Help file indicates is a good choice.
Now go to the Advanced tab on the LinkSys Web interface. Then the Forwarding tab.
On the "Ext.Port" put 8931 to 8931, check TCP and enter your local address (your 192.169.* address), and check the Enable box. Apply and you should be set.
To connect to it from work, use your actual address XXX.XXX.XXX.XXX:8931 as the server address.
If you want, once it's set up, mention your actual IP address and the port number you picked, and I can test it while you are there.
If you LinkSys WebInterface password is still Admin, you should change it. They are popular enough everyone knows the default password.
Hope this helped.