You could print this special spec as an 'Additional form'. Ensure that the bank is set up to allow printing additional forms. When you print a check, leave that box selected as usual. After the checks have printed successfully, a question will be asked whether you want to print additional forms, and here you pick yes. You then select the special 'advice-only' spec and either print, fax or email the additional form as desired.

Default specs are defined on the bank, not the vendor.