activating gdm3.6 themes?

[Arrakaij]

Hi,

i'm using a install from sabayon 11 gnome, and a friend asked me to migrate his kdm theme to gdm3
(i'm using gdm-3.6.2)

to get started, i just downloaded a package x11-themes/gdm-themes and some themes from the internet, but i actually dont get any other thing displaying at login but the gray-sparkled standard login screen.

i googled quite around a bit, trying gdm3setup and using /etc/gdm/greeter.settings, dconf and tweak-tool, reading debug output to get a clue, but i did not manage it do display something else (except for the background)

after reading the offical docs to gdm3 i'm not even sure, if gdm is skinnable at all, except for the background, tho i saw some good ones on the net, claiming they were gdm3 themes

the question is:
is gdm3 skinnable at all?
if yes, how do i actually activate custom themes?

thanks in advance,
Arrakaij