(This is less a set of instructions and more a set of tips for getting and using live ladybugs in your garden.)
Step 1: Ladybugs Go!
Turns out ladybugs can be purchased online relatively inexpensively. I purchased about 1000 of the critters for about $11. A simple google search turns up websites that will sell them even cheaper (between $5 and $10).
The ladybugs that I purchased came in a sack stored inside a box. They were kept very cold on their journey to my house in order to keep them inactive. Once they started to warm up the bag start to wiggle.
To actually use the ladybugs once you have them, simply tip the bag out onto the effected plant. 1000 ladybugs is probably overkill for one plant, but I couldn't find them sold in smaller quantities. Your local garden store might be able to sell you a smaller amount.
The ladybugs will live on your plant, eating all the inappropriate aphids and generally making the plant healthier. Don't worry about the ladybugs sticking around too long -- as soon as the available food source dries up (ie. the aphids) the ladybugs will fly away.