Took me all of 10 minutes to complete tonight, and that counts a trip to the Whitegate AH ^^ The description here is good but it may not be the most clear, so here are my observations on the quest. Note: you do NOT need to talk to any NPCs in Whitegate to start this quest ^^
1) This quest is INSANELY easy to accomplish if you have access to the Halvung (Lebros Cave) runic portal. Part with 200 IS in Whitegate, pop into the Chamber of Passage and off you go to K-6 on the Mount Zhaylom Map.
2) From there, sneak + invis (clusters, leeches, and Phasma will all ruin your day) an follow the path ahead to K-7 when you'll hug the left wall. This leads you into a narrow path and eventually a tunnel with will empty out at L-6.
3) The steam vent that has the targetable blank spot is to the right if you're coming from the Runic Portal. You'll have to drop invisible to trigger the cutscene, but you may want to keep sneak on as there's a Volcanic Leech that spawns around the vent.
4) Click the blank target first to trigger the cutscene. At the end, trade your pickaxe to the target for second CS when the troll will complain about the size of your pick. Don't take it personally, head south, and zone into Halvung (if you can target the Goblin Footprint, you're on the right track!)
5) Zone back into Mount Zhaylom and trade the Mythril Pick to the target to trigger the final cutscene. You'll be prompted to either give the sad troll your Pick or Keep it. I choose to be nice and give the troll the pick which set off some happy music and completed the quest. I'm not sure what happens if you select the second choice (it's mine!), but I don't think it'll change much except the music for the final piece of the CS.
6) You do not lose the pickaxe that you trade to the target, but you DO lose the Mythril Pick.
...and that's pretty much it!