Convert Modules from drupal 5.x to drupal 6.x

Use Deadwood:

The purpose of this module is to automate as much as possible the task of updating a contributed module for Drupal API changes, and thereby simplify the task of porting contributed modules shortly after a new Drupal release.

All changes are made to a copy of your module's files. The conversion process involves searching the module files (i.e., those files with extensions of .info, .install, .module, .inc, .theme and .php) for 5.x syntax and replacing the text with the 6.x equivalent. In many cases, this can be easily done in an automated fashion. However, some of the API changes do not easily lend themselves to search and replace automation. In those cases, and when a conversion routine has not been provided, manual intervention by the module maintainer is required.

Link: http://drupal.org/project/deadwood