[Theming CCK] Seperating multiple values by commas

Hello!
If a CCK field contains multiple values, Drupal creates something like this to theme it:

<div class="field-items">
            <div class="field-item odd">VALUE 1</div>
            <div class="field-item even">VALUE 2</div>
            <div class="field-item odd">VALUE 3</div>
</div>

I'm now looking for a way to display the values just seperated by comma like this:
VALUE 1, VALUE 2, VALUE 3

Anyone maybe knows how to realize this?
Thanks alot for any help!

Noddy