I don't think you can really mess much with the datalink layer (layer-2) from an application program as most of that is generally set by your network interface hardware or your OS's networking layer. However, you should be able to do just about anything you want at layer 3 (network layer) and above. Technically, sockets actually don't exist until layer-4 (transport) of IP. However, the Sockets perl module really starts at layer-3 (netwoking), so you're probably out-of-luck trying to use it to work at layer-2 (datalink).
Les Howard
www.lesandchris.com
Author of Net::Syslog and Number::Spell