[gentoo-dev] Ebuild's that new another packages comfigured source

[Sean P. Kane]

I am very new to Gentoo development and am trying to create an ebuild
file for linux-wlan-ng. Which among a few other things includes the
drivers for Prism2 based wireless network cards. To compile the PCMCIA
driver it needs to have access to the CONFIGURED pcmcia-cs source code.
Assuming that someone has the USE flag "pcmcia" set how do I tell ebuild
that I need "pcmcia source". If this is impossible should I always
download pcmcia a new, configure and install it and then keep the source
around to do the linux-wlan-ng build from? This seems clumsy and likely
to cause people some grief.

Thoughts beyond this: 

Is there a way to keep the source installed for certain key packages
like pcmcia in a consistent way like the kernel sources are kept around?
Maybe have a USE "KeySourceCode" or something?

Thanks,
Sean