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# become root, su or sudo bash
cpan
o conf init /proxy/
# and answer the questions as displayed

Updating software if the appliance has no Internet access, but your desktop has (via proxy)

A variation of the above is also possible, if (and only if) you are accessing the Internet (from your desktop) using a proxy server, and if (and only if) you are accessing the appliance via SSH. In that case you can use SSH port forwarding to temporarily grant the appliance access to your proxy.

You have to select an unused high port number, and you need to know your web proxy addess and port number. In this example I'll use 8888 as the high port number, and let's assume my proxy is at proxy.opmantek.com and works on port 3128.

With plain command-line ssh I'd use the following invocation to establish that port forwarding: ssh -v -R 8888:proxy.opmantek.com:3128 root@the_appliance_name_or_address
For PuTTy, I'd go to the configuration menu, SSH, Tunnels and add 8888 as source port, select "Remote" and add proxy.opmantek.com:3128 as destination. Then I'd connect to the appliance.

Configure the appliance's yum and cpan to use localhost:8888, possibly configure proxy authentication, and things will work as if the appliance had direct proxy access.

You'll be able to use localhost:8888 on the appliance as the proxy address, precisely while your SSH connection is open. Once you disconnect,  port 8888 closes down, and the proxy becomes inaccessible.

Installing or upgrading without any Internet access

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