Any reason not to use ARS? That would allow you to put both your PRI and SIP trunks in the facility groups for now, then remove the PRI later.
Regardless, you'll find the outgoing trunk group in SYSTEM/DEVICES AND FEATURE CODES/<ext no.>/ASSOCIATED EXTENSIONS/OUTGOING. You'll find the trunk group pilot number here (92000 would be ARS, by the way). Fix one phone, then when the list of phones is in the right pane right-click on the fixed phone. Then click on the first other phone, shift-click on the last phone to highlight the whole list. Right-click on one of them, choose PASTE. Clear all the choices except OUTGOING and complete the paste.