Enjoy
Use on 2 or 3 alts, don't think you can use the toon that is the owner of the vendor for xp.
1) create as many vendors as you can right next to each other, you can delete them after you Master to place them in a sales area
2) get alts and/or friends to log off completely (close client) in front of the vendors
3) log in and, without selecting anything else, click on each vendor once (do not open vendor, just select)
4) start macro
5) enjoy your free xp with a beverage!
Add more temporary vendors as your skills increase so that xp goes up even faster, repeat steps 2-4.
macro name: merchant_xp
/ui action cycleTargetNext;
/pause .5;
/ui action vendorUse;
/pause 5;
/mood none;
/ui action defaultButton;
/pause 30;
/macro merchant_xp;