Yes, you can paint them. The secret is no secret, you need proper prep.
Step One: After a light sanding or bead blasting clean the hell out of them. Soak them inside and out in acetone, denatured alcohol, or something like brake clean several times over. Aluminum is porous and any oils that get on it will get into those pores. Even oil from your hands. (You're using gloves with this s**t anyway, right?)
StepTwo: Use a self etching primer made for aluminum. Rustoleum has good one specifically for aluminum and that sets you up to use any other Rustoleum paint for the color and clearcoat if you're going for glossy.
That's it. Poison clean, self etching primer, keep things in the right temperature range, wear gloves, don't breath it in. You get the idea. I always thought these would look good in a wrinkle black finish.