Installing Windows without superdrive or USB
Try using WinToFlash in creating your bootable USB.

I also ran into problems when creating a Bootcamp partition. I also don't have access to a SuperDrive when I created a Windows partition.

First, use WinToFlash on your Windows 7 iso. Please use at least a 4GB USB drive and make sure that you don't have any important files in that drive as WinToFlash will delete all files when creating the bootable USB. After creating the bootable USB, go ahead and create a Bootcamp partition in your Mac drive using this tutorial. Hope this helps.