Try to do it 2 times a week to start. Use it like racers do tempo rides. So push hard for the 10 miles on the ride home twice a week. Also you're going to have to continue working spin. Pretty much drop gears until you're hips start doing the Elvis shake, then click it up one. Once you adjust to a faster cadence, you'll be able to push a third tempo ride into the mix in a week. It's possible after maybe 8 weeks. Then again, you'd be adding racing tools to a commuter ride, so /shrug.

I've pushed a 25 MPH pace for 10 miles in the last two weeks, until my daughter was hospitalized with the flu. But that is, once again, preparing for a triathlon this weekend. So I've probably got 2500 miles already under my belt of dedicated 150-200 mile weeks (sans commuting). Probably another 50 a week in commuting....see what I mean?

Obsession, dedication and a little bit of insanity have to be taken in the right dosage to make things interesting

Good luck.