Google is your friend!*
Turned up another Apple Discussions post that said to press + U at the ctrl-alt-del prompt to bring up the 'visually challenged' tools, and to turn on the on-screen keyboard. This should allow you to log in, then once you are in, remap the keys to something more convenient, maybe assigning the right-hand-side command key to DEL. Unfortunately, I haven't used a Windows PC in ages, so I can't tell you how to do this.
On a related note, I've just discovered that I don't have an key on my MBP. You learn something new every day!
*(Disclaimer: Usually.)