It turns out, that even if you didn't order Bluetooth in the Build-To-Order configuration, you can add it after the fact. Here's how.
Step 1: Get a Bluetooth Module
Purchase the $60 (ouch) Dell Wireless 350 Bluetooth module (you can also find these on eBay for a bit cheaper.
Step 2: Open the Bluetooth Module Compartment
Now, shut down the computer, unplug it, take the battery out, and open the Bluetooth module compartment.
Step 3: Connect the Module
Gently pull the cable out of the compartment and connect it to the Bluetooth module.
Step 4: Seat the Module
Seat the module in the compartment cover.
Step 5: Close It Up
Put the compartment cover on, making sure to not crush the cabling inside.
Step 6: Final Touches
Now you're ready to put the Bluetooth sticker on, put the battery back in, plug the E1505 in, and turn it on. If you're running XP or Vista, it should install the drivers automatically.