PHP-Code on Error-Page

I am looking for a way how to integrate special php-features into the error-pages.

there are two ways how to do it (in my point of view):

1. Change the Textarea on the settings-page to evaluate php code
   • Provide Format filter - known from the create node/comment page - but maybe introduces some security issues (?)
   • Generally evaluate the code - as seen on http://drupal.org/node/28648
2. make a new themeable function - this is my way :D
   theme_customerror_403 and theme_customerror_404 are introduced :D

is anyone interested in this behaviour?
which way do you think is the best?
What do you think kbahey?

Ciao Tobias