Are you using the scriptListener plugin to record the action manager code? if so, change the part of the last line of "DialogModes.NO" to "DialogModes.ALL". Just be sure to set it back to no with this line:
app.displayDialogs = DialogModes.NO;
Thank you for your help Chuck!
The print dialog can be showed with this command:
executeAction( charIDToTypeID('Prnt'), undefined, DialogModes.ALL );