How do you create a subtheme for Zero point?

I already have images in the custom folder for the first implementation of the theme.
A subtheme is an alternative implementaion of the theme with a different set of header images etc.

Since you can't subtheme zeropoint, it seems, you need to duplicate it.

This is my method :
1] duplicate the entire theme folder and rename the copy (as per usual for a subtheme)
2] edit the template.php file in the second instance to change references to zeropoint to zeropoint-theme2

Then a marker file so that when updating, the same changes can be made again in the template.php file.
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I tried to treat it like a regular theme: created a new folder with a new .info file that declared zeropoint as the base theme. But the theme continues to use the main zeropoint files and not the subtheme files.
I just tried putting the modified template.php in the subtheme folder, but that killed the site entirely as it had already processed template.php and would not do it again.
I think it is the hard-wired references to the theme name in template.php that make subtheming not work (the function starting line 91).
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It is a pity subtheming doesn't work as intended in Drupal as that is a much simpler and easier to maintain method that doesn't require messing with the template file.

Cheers
Miriam

I could not find away to make the normal subtheme method work.

The subthemes could not find the _custom folder within the new subtheme folder.
The theme files for the subtheme did not override the base theme. I think because some theme addresses are hard coded into the template.php, as mentioned above.

Cheers
MIriam