[TYPO3] using IProcFunc

[Jeroen Visser]

Hello,
I am busy with adding a category list from commerce to my normal 
horizontal menu which folds out with mouse over. I have been pointed out 
to the function IProcFunc. First off all I followed the example 
media/scripts/example_itemArrayProcFunc.php
The array $menuArr returns the tree that is present. When I am for 
example at $menuArr[400] (catalogs) I should expand the array on that 
point with the commerce category's.

Does anybody done this before?
Are my thoughts about handling this correct? I am looking forward to 
some tips.

Thank's in advance

Regards,
Jeroen Visser