If you don't have it already, you may want to install the stelzbock_stealth theme too. It has some great looking icons that go well with that theme, as well:
http://www.cockos.com/forum/showthread.php?t=5904
In REAPER's Preferences select the
Color Theme tab and under
Theme requests UI images dropdown select the
stelzbock_stealth_ui and apply.
Cheers,
Billy Buck