I was following this article last week in order to apply an authourity signed certificate to my UMP.
However, it was failing due to the CSR being truncated by the Ctrl-P probe utility.
You can get round this easily by running the following LUA script
args = pds.create()
pds.putString (args,"x500_distinguished_name","CN=Common Name for your certificate")
local csr = nimbus.request ("/domain/hub/robot/wasp","ssl_generate_csr",args)
Hope that helps