Optionally depending on KDE4

[hideo]

Hi everyone,

I'm trying to update audio/pacpl to the latest version which has
dropped support for KDE3 and added support for KDE4. By "support"
I mean it offers Konqueror and Dolphin service menu integration.

How do I optionally pull in the KDE4 prefix and base, e.g. 
USE_KDE4=kdeprefix kdebase, as a dependency if either of
these options are selected?  Also, I notice that when these KDE4
options are set, everything the port installs goes in KD4_PREFIX, 
including config, data, doc, and shared files.  Are users expected
to know that KDE4 dependent ports have their config files, for example,
in /usr/local/kde4/etc instead of /usr/local/etc?

Thanks,
Zach