The in-text citation is an abbreviated form (such as “Author-Date”) that corresponds to the bibliographic entry so you’re asking to perform a function that cannot be done by modifying the EndNote citation template.
But a workaround would be to insert the citation then edit the citation to “Exclude Author” and “Exclude Year” which renders the citation invisible (but allows the reference to be listed in the bibliography. Then manually type-in the desired bibliographic entry.