you would need to hand code the few categories you wish to include.
Before making any changes, view source on a power store page so you can see the link code that is generated for the categories you wish to keep.
When you are editing the menu, set the link to be the same as what was in the source code.
For example, I have a category called One, in the source code for the menu, I see it is created as:
<li class="parent"><a href="/ps3/Products_Results.php?Search=1&ProductCategoryID=1">one</a>
so to add this back as a static link in my menu, I would set the name to One and the link to: