If you are comfortable doing the labor involved, the parts should be fairly easy and inexpensive to acquire through the forum. Post a WTB in the classified section if you can't get it from someone already offering parts.
For a guide, the
Pelican Parts Tech Article section is good, but specifically for this, take a look at Mike Focke's Boxster pages:
https://sites.google.com/site/mikefocke2/thetop-itsmaintaince%26replacement
For a downloadable parts manual, use this link and enter "Boxster 986" as the selection.
https://www.porsche.com/usa/accessoriesandservices/classic/genuineparts/originalpartscatalogue/
...handy to have.