I couldn't find this anywhere and it was annoying me, so after some experimenting we've worked out how to equip traits and abilities through macros.
By traits and abilities I'm not talking about combat actions (or /eaction 1 "Light Strike" etc.). I'm referring to the DoL and DoH abilities (such as "Field Mastery").
To equip traits and abilities in macros, it's the same freakin' macro!
/eaction 1 "Field Mastery" will equip Field Mastery to the first slot within the abilities section... not the actions. So:
/eaction 2 "Field Mastery"
/eaction 2 "Wrist Flick"
* This will equip 'Field Mastery' into the second abilities slot and 'Wrist Flick' into the second action slot.