Probably the best way to contact X-10 is to phone their 800 number.
Or you can buy a CM11A with cable from
www.hopco.com for $13.95 and have a spare controller. It has the IBM logo but it is otherwise the same as the unit sold by X-10. Also, you might ask them if they can sell the cable only.
I have no experience nor affiliation with this company.
It is amazing how few e-merchants seem to reply to e-mail in a business like way. Bill at homeautomation.net and Robert at RCI Automation are excellant as is kidstoysplus.com where I have purchased a number of diecast model cars. And other than those three, my experience with e-mail and vendors has been dismall.
Cheers, Jim.