"If I always sit at the same desk, wouldn't that eliminate the HWID issue? I'm thinking of putting MegaLauncher and the DirectX files it needs onto a USB and using it that way."
You can certainly use it, but MegaCheats allows only three HWID changes for monthly plans. Also, keep in mind that any computer you use at the internet cafe must meet MegaLauncher's requirements.
Whether you use a USB drive or not makes no difference; the software recognizes the computer it's running on. You'll need to log in from the same computer consistently.
As I said, it wouldn't be a productive choice. You can buy it if you can use the same computer all the time.