starting completions with =,<,>

[chris s <oberyno@xxxxxxxxx>]

Hi, I'm trying to add to the functionality of the emerge completion for
gentoo linux. For example,

emerge -p =zsh-4.2.0-r1
emerge -p '>zsh-4.2.0'
emerge -p '<zsh-4.2.0'
emerge -p '>=zsh-4.2.0'
emerge -p zsh

are all valid commands. I saw in the manpage that _values does not
support the equal sign. Unfortunately, that's exactly what I need.

Here's a small working example of what I'm trying to do.
http://home.earthlink.net/~oberyno/data/_emerge
The relevant part being 

'--exact[specify exact version]:*::alt:->exact_ver' 

This is what I'd rather have look like this:

'=[specify exact version]:*::alt:->exact_ver' 

Is there any way to fake this? Thanks for any advice.