Nah, you just connect the PS3 to your PC and run an application. No settings need to be changed on PC or router, you just gotta activate the proxy setting in your PS3 for the time being.
I'm using a network switch, though. Might be different for other setups.
Ah, it's unfortunate that the issue appears to be more complicated than just changing the certificates on the server. Would it be possible to use HFW to install new certificates on the user end, install the exploit and switch to CFW?
Anyway, thank you for hard work @bguerville. It says a lot...