well, they most likely have a website so you could scan that to find an ip address and from there it's pretty much recon and that should be enough open up enough opportunities for you to choose from.
What can i get hacking into their website.. ?
Not the greatest thing to have on your machine's history as your ISP is now watching out for you but oh well.
May be you can start off with the default gateway. You can get this information from the DSL Router.