Upgrading from 4.6 to 6.x

I had posted a previous topic (http://drupal.org/node/221416) asking about upgrading a site from 4.6 to 6. While I was able to get most of this resolved, I have run into another issue. When the site was originally built (not while I was around and before I knew about the various character sets), latin1 encoding had been used on the various modules for the site. Now while a number of the tables the modules use have been deprecated and moved over to module tables that support utf8, there are other modules that were built for the site that are not utf8. And I now found out that Drupal 6 lacks the function that was in version 5 _system_update_utf8

I wanted to know if anyone else knew the drupal way of converting a table to utf8 in the newer versions or would it be more sensible to just copy the function(s) over to my migration stage to have this work.

I hope what I've written makes sense. Thank you in advance :)