McNally, 18, signed for the Giants at the end of last season after bursting on the scene with a hat-trick for hometown side Haven in their win over Salford last season.
He was loaned back to the Cumbrian side for 2009 while he completed his A-levels, but now they have finished, he has started training with Nathan Brown’s side, currently third in Super League.
McNally said: “This has been my first full week down here, and I’m absolutely loving it!
“The plan is for me to come and train with Huddersfield from Monday to either Wednesday or Thursday, depending on when Whitehaven have a fixture. I already feel very much at home here.
“The boys couldn’t have given me a warmer welcome, and they’ve made sure I’ve fitted straight in.”
McNally is currently the top points scorer in the Championship and will be looking to end his time at the Recre on a high.