You can't on the 7225.
The 7120 is a FujiXerox machine, FujiXerox machines have the poster option on the copier.
The 7220 is a Xerox machine, Xerox machines do not have that option.
Your only option is to scan the document and then print to get what you want.
Acrobat/Reader has it
You can do it with a program like Rasterbator
You can find more from here.