Check out the ActiveState faq under Upgrading from ActivePerl 5.8.x. Apparently, you can save your 'PPM Profile' thus:

ppm install PPM-Profile
ppmprofile save C:\profile.xml
[download]

Then, when you have installed 5.10:

ppm install PPM-Profile
ppmprofile restore C:\profile.xml
[download]

However (disclaimer), I haven't tried this yet...