Using the Znode Dynamic Schema capabilities you are able to create custom Attributes for your Categories in the PIM.

The general process for this is:

1. Define the attributes you need, and decide the attribute type and details.
2. Create the Category Attribute you need, while choosing the correct type.  See: Managing Category Attributes
3. Add the Category Attribute to an Existing Category Attribute Group, or create a new Category Attribute Group.  See: Managing Category Attributes Groups
4. Then add the Category Attribute Group to an existing Category Attribute Family, or create a new one.  See: Managing Category Attributes Families

Category Custom Groups and Attributes - Where do they show?

PIM > Categories > choose a category