A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Go to 'Page Layout' tab, select the 'Page Setup' dialog box launcher (bottom right corner), click on 'Options' button, (the printer properties dialog box opens), select the 'Paper' tab, then select the 'Custom' button next to 'Size is:', this opens the 'Custom paper Size' dialog box - now put your custom settings in here and 'Save'.
Cheers
Angus