How to add Sort (when clicking on the title) on Content Taxonomy Fields and Node reference.

Drupal 6.15.

Hi,

I hope I post at the right place.

I need help.

I tried to figure out how to add Sort (when clicking on the title) for Content Taxonomy Fields and Node reference.

Here's the situation.

I have a node "apartement". With the CCK I added some fields like Price (integer), Description (text), Location (node reference), Size (Content Taxonomy Fields) Availability Date (date).

In the Basic settings of my view, Style = Table.

When I click on the gear, I can decide which column is sortable for Price (integer), Description (text), Availability Date (date) BUT I AM NOT ABLE to do that for Location (node reference) and Size (Content Taxonomy Fields).

How can I add a sort for that column?

Which hook should I use?

Which is the appropriate method?

I have read this post: http://drupal.org/node/495402 but it not help me too much.

I have also read the documentation about tablesort.inc: http://api.drupal.org/api/drupal/includes--tablesort.inc/6

I really don't know where to start. I am looking for a complete example. Maybe someone can give me some tips.

Thank you.