EDIT: I gave you the wrong code, the correct code is below. I did not notice you had changed the actual in and out effect values and parameters.
Because the parameters are hard-coded in to the main swf file, you cannot change the values, only the parameters of the values. Therefore, if you wanted to use header to link to your forumhome, then you just need to do the following:
XML with new transitions and forum home page link
Code:
<?xml version="1.0"?>
<slideshow randomDisplay='false'>
<image src='cc_hp_head_images/img1.jpg' link='http://fniv.it/vb/forum.php' inEffect='Coarse Blur' outEffect='Wave down'>
<caption></caption>
</image>
<image src='cc_hp_head_images/img2.jpg' link='http://fniv.it/vb/forum.php' inEffect='Coarse Blur' outEffect='Wave down'>
<caption></caption>
</image>
<image src='cc_hp_head_images/img3.jpg' link='http://fniv.it/vb/forum.php' inEffect='Coarse Blur' outEffect='Wave down'>
<caption></caption>
</image>
<image src='cc_hp_head_images/img4.jpg' link='http://fniv.it/vb/forum.php' inEffect='Coarse Blur' outEffect='Wave down'>
<caption></caption>
</image>
<image src='cc_hp_head_images/img5.jpg' link='http://fniv.it/vb/forum.php' inEffect='Coarse Blur' outEffect='Wave down'>
<caption></caption>
</image>
<image src='cc_hp_head_images/img6.jpg' link='http://fniv.it/vb/forum.php' inEffect='Coarse Blur' outEffect='Wave down'>
<caption></caption>
</image>
</slideshow>