I need to modify some .dll files in my install.wim\windows\system32

As you know, there are permissions / ownership? that disallows so. I have this 'takeownership' registry in win7, it makes use of icacls, but the problem is, im using xp to make my win7 setup.. any idea how i can get around this?

I would try a combination of subinacl.exe and cacls.exe to replace the takeown.exe and icacls.exe commands.

subinacl is not part of windows xp, download it here.

Quite possibly also you can use cacls wth XP. Just open cmd prompt and type cacls to see if it is on your version

on Win 7 NOTE: Cacls is now deprecated, please use Icacls.