trigger install is easy on acr, install it just as if you are doing it in an AR, then u slide the safety lever back in, use a pick to lift the spring leg back into its slot.
some people are having a hard to trying to pivot the trigger bow level so that you can then install the hammer, my advice is put the back of the trigger pack down onto the edge of a table, this way the trigger bow can't tilt back.
i have got it down to 6 mins doing a RE and RE on mine.
PS: or if you are brave enough, once the trigger is all in then slide the safety lever in its place and smack real hard, it will go past the spring legs and click itself into its place