What are some effective ways for someone without a graduate degree to increase their chances of getting hired as a lecturer?
Gain specific professional experience in the subject you want to teach.

In my (engineering) department, all of the teaching staff who do not hold PhDs (or are not current PhD students) have industry experience in the subject they are teaching.

In other words, if you are a professional penetration tester, you may be hired to teach computer security. If you work for a major telecom, you may be hired to teach computer networks. Kickstart a successful electronics startup, and you may be hired to teach circuits. You get the idea.

The point is to have some domain-specific expertise you can bring to the table (because university professors are supposed to be subject matter experts, or at least be able to pretend to be). If it's not from research, professional experience can also work.