Confront their dealer Dixon and convince him to stop supplying Bill and Jacob with drugs and alcohol. with a Speech of 35 or the Black Widow perk. Alternatively, Dixon can be killed.
Talk to Jacob and Bill and help them get clean.
Jacob will request ten doses of Fixer, but a Science of 50 will allow for a combination of Fixer, Psycho and Buffout. Alternatively, a Speech check of 50 will convince Jacob to quit cold turkey.
Bill asks for two doses of Fixer, a bottle of whiskey and a RadAway. Similarly to Jacob, Bill can be convinced to quit with a Speech of 50.
The title of the quest is a double-entendre, being both an idiom meaning "it's long overdue" and a use of the word "high" in reference to drugs and alcohol.