NCAA 9-4-b
"If a coach or his nonplaying representative goes to the mound a second time in the inning to talk to the same pitcher, the pitcher must be removed from the pitcher’s position for the remainder of the game. The coach is to indicate the relief pitcher to an umpire immediately after crossing the foul line (see 7-2-c-[5]-[b]-[4])"
Of course, if this isn't the second visit to one pitcher in the inning, the coach can actually hold a conference as opposed to just taking possession of the ball.
By the way, the rule reference 7-2-c-[5]-[b]-[4] tells you all you need to know about the complexity of the NCAA Designated Hitter rule!