Ok here ya go.
First dont take out those 8 little plugs in the back of the 22-4 that say dbx on them, They are confusing and where originaly put there for a differant unit.
Now what you want to do is take the output 1 of your mixer and plug it into the input 1 of the dbx section on the the dx4d (that is the bank of rca,s on the left as you are looking at the unit from the rear ) Then take a line out of the encode 1 out to your input 1 of the 22-4.
Then for your playback and return you would run out of channel 1 of your recorder to the number 1 decode on the dbx unit then on the dbx unit you would take line 1 out to the line input of your mixer.
And just do the same for the rest of the channels.