Any idea HOW to do that?

My own improvements in nonreactivity and interest in others have been largely due to mindhacking; e.g. removing triggers that caused me to fear rejection of particular types, removing negative "ideals" that triggered judgment of self or others, deleting conditioned appetites driving approval-seeking and status-seeking behaviors, etc. (A blog post I wrote on dirtsimple.org in May mentions in passing a bit about how removing a negative ideal/compulsion to be "good" created a mini-renaissance in my marriage, for example.)

I've posted here a lot about ideal-belief-reality conflicts (Robert Fritz's term) which are a primary driver of hypocritical behaviors -- e.g., being obsessed with the future of "humanity" while not being able to be nice to individual humans you disagree with. This is precisely the sort of signaling that will label you as a "jerk" to others. The fewer IBRCs you have, the less often you'll make judgments of others that trigger automatic contempt signals from your body.

(If you feel contempt for someone in a real-time social situation, trust me, other people are noticing, and judging you accordingly. The only real fix is to make it so you don't have the contempt in the first place.)