HFS is one of CT's current training principles. You don't need to be on Indigo to follow it, but the full Indigo routines are pretty intense and shouldn't be attempted without Indigo or above average recovery ability.
If you check out the Indigo logs, you'll surely find a lot of examples of what people are currently doing for their HFS work. Also, there's ton of info in the livespills.
In short, HFS is High Frequency Strength work. You pick 3-4 basic movements for different patterns (ie. Military Press, Squat, Bench Press) and perform them 4-5 times a week. You want to select a weight that is not too heavy and that you can dominate on every rep. No rep should ever be slow.