MAC Championship or bust.

No. If you're the regular season conference champs but don't win your conference tourney, you get an automatic bid. Akron was assured of an NIT bid regardless of what happened in the MAC Tourney.

i hate when we start talking NIT bids.  Kind of embarassing and rarely is based on merit.

There really isn't any way for a team (MAC or otherwise) to lock up an at-large NIT bid.  Beyond the auto bids Ted mentioned, the selection committee goes by a set of "principles" for naming and seeding the field.  I think there are three that are probably overarching:

"The committee shall select the best available teams to fill the NIT field."

"There is no limit on the number of teams the committee may select from one conference."

"On the ballot, each committee member shall identify not more than 32 teams that should be invited to the tournament based upon their successful play to date."

In other words, the committee members select the teams that they think should be in the tournament, no matter what their record, no matter what their RPI, no matter their strength of schedule.  It's the "best" teams available, however they define "best."  They can rely on whatever biases they may have and may be influenced by whatever factors (including TV ratings and potential attendance) they choose.  So, the best thing is to forget about the NIT and concentrate on winning the MAC Championship.