That's a shame about letting their domain name lapse! They should be able to get it back fairly quick though in my experience.
I have used Hamachi before for GTL when the lobby was down a few years back (!). It worked great and it's very easy to set up and get going as far as I remember so it shouldn't be a problem for anyone.
If I get the chance I will look into it again and write up a step-by-step and post it here for others to add their comments, refinements, tips etc. to the process.
I'm gonna give P&G a swerver tonight as I don't have it installed yet so don;t want to go in until I have tested it at least.
See you soon