I've never seen anything regarding anti-lag when it comes to running Halo mac, so I can't help you there. As for dev trainers, right now there's one known working-ish program.
The Cheat! and here's the
UB version that someone compiled. The program is designed as a universal trainer, but it means having to search for certain values and is quite a hassel. Aside from simple things like ammo count and such, it's not very useful. There's been a lot of talking about 3rd person
here that has semi-reproducable results. That's everything for trainers and hacks for mac that I know of.