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:
Define the attributes you need, and decide the attribute type and details.
Create the Category Attribute you need, while choosing the correct type. See: Managing Category Attributes
Add the Category Attribute to an Existing Category Attribute Group, or create a new Category Attribute Group. See: Managing Category Attributes Groups
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