I must not be all there today. Well, I'm sure you can still take off the bumpers. They're the ones that wrap around and come up above the headlights, right? On the 92-99 ones (my favorite, no offense), the grille is a part of the hood, and the bumper stops below the lights. Wow, the 2000-series Bonnevilles are far more like my sister'* 2001 Alero, both externally as well as dash-wise, than the 92-99s. Strange.
Well, you can still paint the doors from the bottom up to where the bumpers end by taping off the rest. This should give you a good rice look, but since you're going for a body kit more so than some crazy paint job, I hope, you should still stick to getting a mold if you're going to have a body kit.