RC Master has a No Deaths/LASO speedrun of the Halo 4 campaign on his site. If you follow his guide to the letter and don't delay, you'll unlock the speedrun achievement as well, as his playthough clocks up at 176 minutes (including preamble and load screens, so that's a few minutes you can shave off).
Basic rules of thumb for a LASO playthrough:
- Avoid fights where possible.
- Take advantage of speedrun glitches (particularly deloads or out of bounds. This can make levels like Shutdown and Composer incredibly short compared to their regular runs).
- Most assisting glitches work better for SLASO attempts (Single LASO) rather than in co op, so you may find a SLASO run more effective for your playstyle than a co op one.
- Melee, Melee, Melee! I can't stress this enough. With blackeye skull on you have no shields, that may sound hard, but it's easy when you combine it with the takedown strategies for Elites. Never bother shooting at Elites unless you can plasma charge their pistol, the faster option is to run at them and melee, each hit will restore your shields, and if you circle the elites much like you would with a hunter, you can restore your shields while doing an assassination or beat down.
- Always take care of mook enemies first, Grunts and Jackals in numbers will decimate you no matter how fast you melee to restore health.
EDIT: As of 2/12/2014 this achievement may be glitched for some people. Runs don't get recorded when you complete them so the achievement may not unlock. Check your stats on Halowaypoint to verify if the run was recorded or not.