Thanks, my plan was to use the /f option but I still need to know what I need to put into the xml file. The only ECFG files I have were generated by EsriRegAsm which doesn't help. Here's what I extracted:
<?xml version="1.0"?>
<ESRI.Configuration ver="1">
<Categories>
<Category CATID="{B56A7C42-83D4-11D2-A2E9-080009B6F22B}">
<Class CLSID="{AEDF990E-5F53-408D-961B-1789073DE1CA}"/>
</Category>
<Category CATID="{B56A7C4A-83D4-11D2-A2E9-080009B6F22B}">
<Class CLSID="{E9E81DA7-A70D-43C1-94EA-89C345ED29CE}"/>
</Category>
</Categories>
</ESRI.Configuration>
Just by guess I added an id property to the Category node but that didn't work.
It did raise a question about the location of the ECFG files. I have installed my add on's to Desktop 10.2 but the only ECFG files are listed under Desktop10.1 even though I have folders for 10.0 and 10.2. Copying the files to Desktop10.2 didn't make any difference.