Have a look at the N4ATS site
http://www.n4ats.com/?Band_Data_Cable_Infoit lists the band switching cable info. Actually both ends are standard connectors and so this would be easy to make up yourself.
http://www.n4ats.com/?download=D4000019_Schematic.pdfALC and PTT are straight phono sockets to the FT-2000
Be careful with drive level. You may wish to use the service set up to adjust them for each band ensuring you don't overdrive your amp.
73 G8UBJ