There's no such thing as a "McHill High School diploma." Colleges assess diplomas from accredited high schools. If you're referring to a specific school with a similar-sounding name, or a home-schooling program using "McHill" as a designation, you'll need to provide more information.
Colleges will look at the accreditation of the high school. If the school issuing the diploma isn't accredited by a recognized body (like a state department of education or a regional accrediting agency), colleges are less likely to accept it.