I have a few command line utilities to install. These need to be run
from multiple directories where they are not present.

So, I want to add my folder to the end of system path. These seems to
be easy enough to find in the registry, either:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Session
Manager\Environment\Path
or
HKEY_CURRENT_USER\Environment\Path

depending on whether the user wants to install for whole machine.

But it's easy to replace, but how to I get the current path value and
append on to it?

Thanks, J