Mac and External anntenna

Hi,

I have an iMac G4 and a wireless network with an Apple extreme base
station. Since the base station is on the 4th floor and the computer
is on the 3rd floor, I was looking to attach an external antenna to
the iMac. To the base station is already an external antenna attached.
The Quickertek antenna. Is there a way to attach a cable to boost the
signal to the iMac? Did anyone know how to do this? I'm not afraid to
drill holes in my computer.

Thanks for any help.

Andreas