This tactic is to kill the opposing ACU without destroying the base, there are multiple ways to achieve this:
They range from Tactical Missile barrages, masses of gunships and Bomber Raids to Artillery strikes, i.e. the Mavor or Scathis, whilst observing the ACU with an Omni sensor radar. Skilled players may try to Air Crash a powerful unit, such as the CZAR.
Considering that all commander units and most experimental units have Volatility in one form or another, this tactic is extremely hard to pull off unless your enemy's base has ALREADY been destroyed, in which case this tactic is useless, or the ACU is out in the open working on a firebase or building a mass extractor. Otherwise, the use of inaccurate tactics such as using a Scathis becomes useless or inefficient. Most players are smart enough to keep their Armored Command Unit within their base, where it is safer due to defenses and cannon fodder, so find a way to bring your enemy's commander out into the open, such as luring it out with a treat like your own commander (which is can be risky, as they could reverse this tactic on you).
Pulling this off intentionally requires a high amount of skill, considering that you have to get your enemy's commander out of it's base to destroy the ACU and NOT the ACU's base.