Can anyone explain how tie breakers are determined for the conference? Specifically, in a conference of 16 where 8 teams make their conference tournament, if teams 8,9, and 10 are tied, what determines who makes it in?

I believe first tie-breaker is a team's record vs the other team tied with them. Not sure what the next tiebreakers are if that doesn't resolve the tie.

In the old days if the teams played twice and split, the winner of the second game got the higher seed. Not sure if that's still the case.

This is the most common method from SEC rule book, Big 10 and Big 12 are written almost exactly the same.

The following procedure will be used in the following order until the tie is broken:
Won-lost results of head-to-head competition between the two teams.
Won-lost record of the two teams versus the No. 1 seed (and proceeding through the No. 14 seed, if necessary).
Coin flip by the Commissioner.

Three-Team Tie (or more)
When three or more teams are tied, the following procedure will be used in the following order until the tie is broken. If two teams re- main tied after a tiebreaker provision, the two-team tiebreaker formula will be used.
Best winning percentage of games played among the tied teams (Example: Team A is 3-1, Team B is 2-2 and Team C is 1-3 - Team A would be seeded highest, Team B second-highest and Team C lowest of the three).
Best winning percentage of the tied teams versus the No. 1 seed (and proceed- ing through the No. 14 seed, if necessary).
If two teams remain, coin flip by the Commissioner.
If three or more teams remain, draw by the Commissioner.

For the purpose of seeding, if an institution is precluded from participating in the tournament, such institution will automatically be seeded last. However, for the purpose of breaking ties, that team will remain where it finished in the regular-season standings BEFORE being seeded last.