Chucky,
Do the work PCs behind the firewall have access to the Internet?
If they do, go into their setup options, look for the connection options, and see if they are using a proxy to get to the internet.
If they are, write down the IP addy (or name) and what port they are using (usually 80 or 8080).
Pull up the RC5 client config, go to option 2 Buffer options, then Option 6, Keyserver<-->Client connection options.
Then select option 6, Firewall/proxy Protocol. Select option 1, HTTP.
You should then have an option 7, Firewall Hostname. Enter the IP address (or name) of the proxy used by your Internet browser.
Save settings and exit. If you have the cow in the systray, right click and select fetch, flush, or update. Check the connect messages to see if the client is able to establish a connection.
Another thing to try is to find a DNET proxyserver that listens on port 80, get the IP address, and specify that in the keyserver options under the Buffer options area of the client, along with port 80. It would look like this: 24.94.16.192:80 (that isn't a dnet addy)
If you are flushing to Mikas, then choose one of the round robin servers that listens on port 80, and specify that server's IP address as the keyserver name, and try the fetch, flush, or update and see what you get. I use clueless.2y.net, port 80:
24.94.16.192:80
Try that and see if it works. If not, another alternative is either sneakernetting from home, or fetch/flush via email.