It's fairly simple. Just head on over the official Capcom USA blogs—Capcom Digital, to be precise—and offer your suggestions in the comments. Come August 1st, the public decides with a democratic vote what Achievements make the cut. Sounds fair and fun.

My suggestions are:
One Breath Title Read - Speak the full name of Super Street Fighter II Turbo HD Remix without taking a breath. (Requires headset)
Perfect Panty Shot - Pause the game at precisely the right moment during Chun Li's "spinning bird kick."
Unlock Sheng Long - Ten perfect tie-rounds with M. Bison. You must also jump down, turn around and pick a bail of cotton. (Requires Xbox Vision Cam)

Okay, now it's your turn. And no stealing my ideas! They're totally copyrighted.

You Decide! SSFIITHDR Achievements! [Capcom Digital]