You can fly to Bakersfield via SFO or DEN (United (Express)) or PHX (American). Probably wouldn't have helped you any - many more options to LA-area airports and quicker to go there and rent a car. And the BFL flights are likely much more expensive than LA flights too.

The Vegas Amtrak bus to Bakersfield (connecting with San Joaquins) runs 3x per day and stops in Tehachapi. You'd need to have somebody meet you there. Hardly a useful option. Kern Transit has a few more schedules (on the Lancaster bus) that stop in Tehachapi, but that doesn't improve options dramatically.

Another hardly-useful option, possible only if you're in LA and it's not a weekend, is to take Metrolink to Lancaster then catch the Kern Transit bus to Bakersfield, which stops in Tehachapi (at K-Mart). But if you're already in LA you already have a car, right? Just a slightly longer commute.

Finally, if you go to an Espee convention in Tehachapi, you're going to go to see the Loop. Isn't that one of the reasons to meet there? So you need a personal vehicle (preferably with a little ground clearance).

Still, looks like fun. I might try harder to arrange some time off (from work and/or the family) and go next year if it becomes a regular thing. And I do have a car and am willing to make the 6-7 hour drive.