Sure - just go to the link above, hit the guests link, then pick a squad out of the list that says they're open to guests. Then just fire off an e-mail to the CO. (the links will open an email to the CO of that squad). It's totally simple, you can sign up in 5 minutes and be flying in tomorrow's TOD. Make sure the CO gets back to you and confirms that you're in.
Good news Rude - will be great to see the 13th there! It's a bit trickier for entire squads, so again, make sure you have confirmation on this and have recieved your mission assignment. If you haven't heard from anyone directly yet, you will need to try and get ahold of someone. Otherwise you'll be all dressed up with no place to go tomorrow night.
This really is rather late in the game to be signing up for tomorrow's frame, but the TOD takes a week off next Friday, and Series 2 of the TOD starts the following Friday. So there's plenty of time to get organized and signed up for that.