I wish you the best of luck in your exploits. I did the same thing a few years ago. For the most part, some of the levels aren't too difficult to do this on. My rules were pretty basic: Legendary, no damage from enemies on foot or in a vehicle, all tricks and glitches permitted. I found ditching vehicles and going on foot most of the time made it simpler. Managed to pull it off so far on Pillar of Autumn through extreme luck, Halo was simple because I killed my marines and skipped 2 of the 3 areas in the last portion, Silent Cartographer was a slow and really drawn out experience but I took advantage of pre-set warthogs loaded with marines to ambush enemies in known enemy spawn areas, AotCR I took advantage of the no-enemy glitch from jumping down from the first bridge, and 343GS/Library were pretty simple since it's mostly just the Flood. Never pulled it off on T&R, TB, Keyes, or The Maw though.

: In regard to H1, though the idea would be applicable to other games too, I've
: just posted a new article Zero hit and minimal hit , concerning the
: rather extreme challenge of getting through a level without ever taking a
: hit - even the slightest one. It's something I've been trying on and off
: in AOTCR for quite a while, as a step up from 'zero health loss'. More
: specifically I've been trying it on Legendary on foot, with the rules of
: my kill 'em all speed runs (I'm really not into sneaking past covies; I
: prefer to leave them horizontal). In the wee hours of this morning I
: finally reached the control room completely unscathed (hah, who needs
: armour?), so I've posted the article at last. Sometime maybe I'll make a
: movie out of a run - the tactical aspects are quite interesting.