First of all, if there is a tie, no-one is crowned “champion”. They are co-champs, regardless of any tiebreakers – which are only used to determine seeds.
In your scenario, HC would have to finish ahead of CU for LU to prevail in the tiebreaker. If head-to-head record doesn’t break the tie, then you look at each team’s record vs the 3rd place team, then the 4th place team, etc. If CU is ahead of HC, then that would break the tie in favor of Bucknell – since BU has a better record vs CU. Also, if CU and HC are tied, then BU also prevails in the tiebreaker due to a better RPI.
Thus HC has to pick up two games on CU in the final three games for LU to prevail in this scenario. IF HC were to beat BU – and that’s assumed in this scenario – it would be remotely possible. HC hosts CU the final game, so a win there would pick up a game. Then they’d have to also either win at Army and have CU lose to either Navy or LC. OR if they lost at Army, then CU would have to lose to both Navy and LC.