The following command adds the rule contentrule to the 20.200.25.94 Virtual Service:

curl -k "https://bal:1fourall@20.200.25.100/access/addprerule?vs=20.200.25.94&port=80&prot=tcp&rule=contentrule"

Response: 

<?xml version="1.0" encoding="ISO-8859-1"?>
<Response stat="200" code="ok">
<Success>Command completed ok</Success>
</Response>