An adapter should be easy enough to build. Who knows though, you might just get lucky and not even need one. For only $3 I would buy it and see where you end up.
I think I would go with a hardware adapter rather than a software solution. What if you need to use the keyboard in dos, or to make a change in the bios? A hardware solution would always be active.
Another thought..... Is the laptop keybaord being sold as an internal replacement keyboard for a laptop, or as an external? If it is a replacement then you will have to do what you are planning, if it is an external keybaord, then it already has the electronics inside it to just plug it into a computer. (laptop or desktop)