As far as I can tell he's saying he was changing the weight and working up, but the part about "then back to 4 and 6" is a little unclear.
My interpretation typed up as a bench workout would be
95x10
135x8
185x6
225x4
255x2 for 5 sets
Then I'm guessing 255x4, 225x6, then you'd just start pulling weight off each set?
Granted arnold used a lot of weight so he probably had the chance to do a lot of drop sets.
I've done them for bench and curls before just using lots of 10's.
So you'd do like 185x8, 165x8, 145x8, 125x8, etc until you have an empty bar or just can't move.
I hope that makes sense and is correct haha