Take a look at this link for a progressive recoil spring from BHSS.
I imagine if the slide is easier to rack, the spring may be easier to install. You might call BHSS and ask them these questions. I imagine they are interested in these accessibility issues... to keep us all shooting!
A customer testimonial:
“from Neil:
I just received and installed my new 18# progressive spring into my Hi Power…let me say before installing I was having the blasphemous thoughts of having my slide cut with front serrations to help my old arthritic hands. Well friend, NOT NOW! after installing it is much easier to rack and I have banished those thoughts. “
Cheers,
Tim