How can someone inexperienced break the touch barrier?

Physical touch is not a bad thing. whenever I'm physically touched by someone I'm interested in, it makes me feel really good inside.

now, if you want to give him a hug, you have to start slow. touch his arm or shoulder or something when he talks, and touch when you greet him
starting slow might help you overcome the touch barrier. it sounds like it is really a difficult thing for you.

if you want a hug, just open your arms, when you or he is leaving. and ask for a 'goodbye hug'

Before you or he leaves, just try opening your arms and ask if you could get a quick goodbye hug. or instead of opening both arms open one out so it's a simple one arm hug

I know this may seem silly, but I've found the easy way to hug someone for the first time is to be goofy about it. Waggle your arms around and be silly, or jokingly hug him after someone makes a smart ass comment at him. It'll give you the opportunity to judge how he feels about it.

Granted if you're a naturally shy person that might seem to out of the ordinary, I myself am fairly quirky and have no shame.