I already posted that this cannot be done. It's controlled on the server.
The vendor that uses currency is the one that sells the loot boxes in this game. They made it cost this server-side currency instead of easily-hackable gold this time around.
That stinks. Heka Chests being totally in-game-currency based was a pretty nice thing to have, if you weren't buying their helix crap. Sad to see that is gone in this one. Oh well.
Just a heads up to anyone that has Twitch Prime (free for Amazon Prime users)
Free content pack.