my concern would be the jacket holding up while sliding across the ground. If the jacket disintegrates then it won't matter how you've affixed the armor. My vote if you want to wear a fashion jacket would be to wear the under armor (fwiw forcefield makes a shirt as opposed to the cheap porno looking mesh stuff out there).
Cowboy is correct. Fashion leather is usually in the 0.7mil range of thickness, whereas riding leather is usually in the 1.2-1.5mil range. That doesn't sound like much of a difference, but believe me, most fashion leathers will shred as soon as they hit the ground. Beside the leather issue, the stitching they use is just not designed to put up with the forces seen in a motorcycle crash. Save your time, money and skin and just look for a dedicated riding jacket who's looks you can live with.