Yamaha DTXpress/DTXplorer/DTXtreme

Hi all from the stormy Shetland Islands,
Just got the excellant DTXpress2, the manual is a bit confusing as to 
how many extra pads you can fit and assign.
Apart from inputs 9/10, can you use a 'Y' cable on say a cymbal input 
and assign an extra pad ?
Hope to hear from you