The Apple iPad doesn’t support a mouse, only a bluetooth keyboard.
Citrix have been smart enough to include this in the Citrix Receiver for iPhone and iPad. They call it the Wireless TrackPad.
Check out this video:
Its easy to set up:
On your iPhone open Citrix Receiver and press the mouse icon in the lower right corner of the screen
Start Citrix Receiver on the iPad and launch a application. Touch the middle top of the screen to show the Citrix Receiver Toolbar. Press the “Pair” button.
Confirm the connection at you iPhone – And your done.