Patty at the Hilton Garden Inn Seaworld has had good luck with her NP 12's by making an AUX TRAY extension from poster board and using the configuration below to allow her to print the legal sized reg-keypackets from the top (fold-down) AUX TRAY with plain letter sized paper in the bottom tray. Using the AUXTRAY for the legal sized stock does cause.

The Tray extension is absolutely necessary since the paper support on the AUX TRAY is not long enough to support legal sized stock. Use cardboard or poster board cut to 8.5 by 14 inches and then cut a notch about 1 inch square out of the left corner where you insert the support into the AUX TRAY. This notch keeps the support from triggering the paper sensor so that the printer will not try to pick up and feed the support. Now tape the support in place and load your registration keypacket stock on top of it. Another option is to turn the printer and place it up against something to direct the legal stock upwards as shown in the picture to the right.

Resize the bottom tray to letter size and load it with plain while paper.

The printer will have to be re-configured to draw paper from TRAY 1 first (SOURCE=TRAY !) and to set the AUXSIZE to LEGAL

IBM Network Printer 12
Configuration Page