Had someone pm me to see how I'd scheduled install / pre-load for off-peak, so figured I may as well post it here too. This uses the basic Windows XP system, but you can get 3rd party applications that may provide a cleaner interface or options for scheduling a start and stop time and maybe bandwidth limiting settings. I've never gone looking to any great degree. Oh to be on a plan / ISP that doesn't have this peak/off-peak rubbish or a decent range of free local steam content hosting.
If you haven't paused the preload (or any install for that matter) before closing down, then it should automatically resume when Steam restarts. The -applaunch option shouldn't be necessary.
Don't worry too much, those who got it early AND got ripped off at retail can't play yet either. Snag An Early PC Copy Of Borderlands? Good Luck Playing It | Kotaku Australia
Fantastic TI It works! Now to use my off peak every month...yeeeehaaaaaa I'll rep you when it will allow it. Cheers.