Got it!!!!!
Nothing's impossible.
1. Locate this file: "/System/Library/Frameworks/ApplicationServices.framework/Versions/A/Frameworks/PrintCore.framework/Versions/A/Resources/PaperInfo.xml"
2. Make a backup in case you screw up. It's not my fault if you do either.
3. Make a copy on your Desktop.
4. Open the copy in TextEdit.
5. Make a new entry like the others, don't copy from here:
Code:
<key>com.apple.print.subTicket.paper_info_ticket 2</key>
<dict>
<key>PMPPDPaperCodeName</key>
<string>Half Letter</string>
<key>PMTiogaPaperName</key>
<string>Half Letter</string>
<key>com.apple.print.PaperInfo.PMPaperName</key>
<string>Half Letter</string>
<key>com.apple.print.PaperInfo.PMUnadjustedPageRect</key>
<array>
<real>0.0</real>
<real>0.0</real>
<real>360</real>
<real>576</real>
</array>
<key>com.apple.print.PaperInfo.PMUnadjustedPaperRect</key>
<array>
<real>-18</real>
<real>-18</real>
<real>378</real>
<real>594</real>
</array>
<key>com.apple.print.PaperInfo.ppd.PMPaperName</key>
<string>Half Letter</string>
<key>com.apple.print.ticket.APIVersion</key>
<string>01.00</string>
<key>com.apple.print.ticket.type</key>
<string>com.apple.print.PaperInfoTicket</string>
</dict>
6. Change the "<real>###</real>" values to suit you. The first two I didn't touch. The next two are the dimensions inside the margins. The next two are the margins. The final two are the dimensions outside the margins. I don't know what units these are but shown here is 5.5x8.5" with 0.25" margins.
7. Change the order if desired. I made mine second.
8. Copy back to original folder and authenticate with master password.