Changing location of iTunes Download

I need to change the location on my computer where all iTunes software downloads are installed. Not where new music will be stored in the iTunes library folder (that I know can be edited), but whenever I open up iTunes and it has a new software update for me, I want to change the location of that update folder. Currently it goes to my C: drive, but my C: drive is very small and doesn't have enough hard disk space. I'd like to save future iTunes software updates to another drive on my computer.

Please help. Thank you.