Got the ATEN/IOGEAR 2L-5301P kvm cable today.
Checked out the cable with a multimeter and the pinout of the 2L-530xP cables seem to be:
kvm 1 (red) - vga 1 (red)
kvm 2 (green) - vga 2 (green)
kvm 3 (blue) - vga 3 (blue)
kvm 4 (key data) - ps2 key 1 (key data)
kvm 5 (key clock) - ps2 key 5 (key clock)
kvm 6 (rgb rtn) - vga 6,7,8 (red rtn, green rtn, blue rtn)
kvm 7 (gnd) - vga 5,10 (gnd), ps2 key 3 (gnd), ps2 mouse 3 (gnd)
kvm 8 (mouse clock) - ps2 mouse 5 (mouse clock)
kvm 9 (+5VDC) - ps2 key 4 (+5VDC)
kvm 10 (gnd) - vga 5,10 (gnd), ps2 key 3 (gnd), ps2 mouse 3 (gnd)
kvm 11 (mouse data) - ps2 mouse 1 (mouse data)
kvm 12 (pc data) - vga 12 (pc data)
kvm 13 (hsync) - vga 13 (hsync)
kvm 14 (vsync) - vga 14 (vsync)
kvm 15 (pc clock) - vga 15 (pc clock)
ps2 mouse 1,4,6 - not connected
ps2 keyboard 1,6 - not connected
vga 9 - not connected (pin removed)
vga pin numbers based on:
http://en.wikipedia.org/wiki/VGA_connector
ps2 pin numbers based on:
http://en.wikipedia.org/wiki/PS/2_connector
The cables are not very thick, so I wonder if poor shielding is to blame for the ghosting problems reported in user reviews.