Open up a blank Nuke submission dialog, enter in the values you'd like to set as defaults, i.e. host.processors=4 for a reservation, then click the "Set Defaults" button at the bottom of the submission dialog. Now you can cancel out of the dialog, then go to File > Save Preferences.
This will set a default preference for this user.
You can make this a studio-wide default by setting a Preference Default to a central location & pointing all GUIs at the preference default. Anyone can add to the studio-default, simply configure another submission window, set the default, then save over the old file.
See section 4.10.1 in the user guide.
http://pipelinefx.com/docs/