I'm an Asian guy and it has always been very difficult for me to get glasses that fit my flat bridge. I recently went to get new eyeglasses at my local optician and inquired with them about nosepad installation on plastic frames. They said they can send them out to have nosepads installed on virtually any plastic frame. There is some company that does this that they contract out to. The service actually shaves off the existing plastic nose parts and polishes the frame so it looks like new, and installs adjustable nosepad arms and pads on the frame. I'm quite happy with the result, it looks like it came from the factory. Ask for silicone pads, they are very comfortable and don't slip as much too. The place I went to is The Focal Point Opticians in Berkeley, CA: http://www.focalpointopticians.com/
Cost is $65. and it takes about a week since they don't do it there but rather send it out. If you are in SF however, I've heard this place is good and they also have this service: http://www.invisionopto.com/
The optometrist there is asian himself. BTW, I got these frames really like them so far: http://www.bartonperreira.com/m/show_style.php?id=1028
I also got a custom e clip sunglass clip to go with it and it looks great with the glasses: http://www.clipon.com/
The owner of The Focal Point is also the inventor/owner of the e clip.