Custom Paper Size (irregular) paper tray calibration

[proditus]

Hello,

I own an IPr C6010 and need to print on a Custom size paper (irregular size as per Canon) 8.75x11.51. I am trying to align the paper tray but this size doesn't show on the drop down list of that Deck #. I have assigned the media and the size on CWS. Can somebody help ?

Thanks,
Berti