I’ve installed wss 3.0 and extended the default web site as a virtual server but the option for wss adapter was still grayed out. After that i’ve only instaled wss 2.0 sp2 and after that i could install the wss adapter.
It looks like wss 2.0 is mandatory for the installation of the adapter but after that can be also used with wss 3.0 or Moss.
I am not sure but i think that if i wan’t to use the wss adapter with MOSS i have to install wss 2.0 on MOSS server(machine) because this is the only way to install wss adapter.