HUMAnN 2 and 3 do not bundle KEGG pathway/module definitions, so we can’t directly quantify those functions from within HUMAnN. If you can download the module definitions and adapt them to HUMAnN’s format you could then run HUMAnN with your KOs as input and point to those pathway definitions to quantify them.
Yes, you would need to supply a file of KEGG pathway/module definitions to HUMAnN to do this though. That is not a file we currently bundle with the software.