This won't work for everyone and I am proof of that.
I'm 83kg. I did stronglifts for a good 8 months, then moved onto the beginners program for 4 months.
I can now squat 140kg, deadlift 180kg and bench.... 75kg.
Yes my bench is so piss weak it's annoying to the point that I'm thinking of stopping altogether.
My chest just doesn't respond to 3x8 bench, and I just will not progress. Example one week I'd do 65kg 8, 6, 5.
Then next will be 7, 6, 6, 4,
week after 8, 5, 6, 4... and so on. It will probably take me 1-2 months to add 2.5 kgs and that will then feel heavy as shit.
Also I noticed my upper body (esp. chest, tris) rarely feels sore after doing the beginners program.
The only way I can get my chest/tri's sore for days is by focusing on them for 1 hour 1-2 times a week by doing:
drop sets,
heavy/forced negatives,
heavy flyes,
close grip bench,
dips,
using db's instead of bb...
This is how I believe I'd get my bench up. Not by doing 3x8 3 times a week which barely does anything for my chest.
The question is how to incorporate it into the current beginners workout, the simple answer is you can't. Which is a pity since my legs/back are still improving.