Sloping HPF / LC questions

Newby on the production side just getting into this. Using Elements 8. Basically I am trying to figure out how to set up a type of sloping LC. What I mean by this is a want to set up a HPF that gradually gains up, much like I would reach up and turn down the low freq on my mixer when I’m mixing into a new track live at a gig. I’ve been googling and searching for days because I know I probably sound like an idiot on here, but figured I’d ask the subject matter experts. I’ve discovered and found automation and can get that to work fine, but it’s an instand on/off with no slope. Help and thanks in advance!