My favorite implementation (can you tell that I'm a geekette?) of a feminine hip is with quilt batting under a "long line" control brief. These briefs extend down to cover the top of the thighs a bit, so they help in smoothing out the transition from the padded portion to the non-padded portion.
I cut several ovals of quilt battings, about 1.75 times as long as they are wide, each succeeding one being 1/2" - 3/4" smaller than the previous one. I stack these ovals on top on one another. This stack of battings will now add curves anywhere you want. After donning the control briefs, I slip the stack of battings into place, the largest oval to the outside. Having the largest oval to the outside will present a smoother silhouette. I use two small "pads" for the derriere, and larger ones for the sides.
To make the stack of battings easier to manage, I glue the layers together. If you are handy with a needle and thread, you can add a "pocket" on the inside of the control briefs to hold the pads in place, making bathroom excursions quick and hassle-free.
You can email Nicole who has has her own Web Page at http://www.europa.com/~nqa/trans/trans.html.