Once you have removed the majority of the wax from the carpet using one of the other methods recommended, try Goo Gone. I have to admit I have never used it on wax, but I love it for taking sticker goo off of things! It even works on gum (I have done that)!
So, if it doesn’t work on the wax, it will still not be a waste of your money, IMHO. The bottle says it works on grease, stickers, tar, gum, crayon, tape, make-up, oil, wet paint, scuff marks, shoe polish, tree sap and asphalt. It is a citrus-based non-toxic cleaner.
I believe Citra-Solve is similar, but I have never bought or used it.