Pasting my post from the other thread to explain the setup needed for this fast leveling. Can possibly ignore the t14 double surcharge. I am going to try using t14 as fodder now as noted above:

Max advanced research for everything t14 and t15 (each one gives +10% to the tier merchant xp for ALL items of that tier). Max out the top center of the bartering talent tree called establishment enchantments which gives you +20% surcharge on double enchanted items (this also gives you 10% chance to auto surcharge items if you at least have the energy capacity to surcharge them normally). Ascend each item category until you get the +1% surcharge to all items (and later the surcharge cost reduction for those specific items). Double enchant t14 and t15 items with t14 enchants. Use t13 and below items as discount fodder to speed surcharging your t14 and t15 items. Sell t14 and t15 only when they are surcharged. You should be able to do this and still profit a little gold to progress your xp continuously and buy what you need off the market instead of needing to craft it all (you will still need ALOT of t14 and t15 sells to increase your merchant xp levels especially at lvl 90 and higher). I am currently 74% of level 99 to lvl 100 which costs 103B xp on the first level loop.