I'd give you the pro-tip on how its done, but then I would be handing johnny-come-lately the trophy. Figger it out yourself. Not my job to teach.
It has been presented. You didn't see it. The tactic is there, and anyone can do it. It's not just a soldier/engi thing.. but anyone versus engi can drop engi blockers with this one handy trick.
God you're thick. Did you even read the logic, or are you just mad I peed in someone else's cheerios (coincidenally, that had nothing to do with you) So, I will take this time to tell you the same thing... since you obvious cant read or take your own advice. Have a decent argument with valid reasons, or dont walk into the line of fire. Besides, nothing you've added thus far, has been anything but smug ignorance.
Mostadio gave you all the information you need to not suck. Use it.