The following command uploads a custom WAF rule fule called CustomRules.conf:

curl -X POST --data-binary "@CustomRules.conf" -k "https://bal:1fourall@20.200.25.100/access/addwafcustomrule?filename=CustomRules.conf"

Response: 

<?xml version="1.0" encoding="ISO-8859-1"?>
<Response stat="200" code="ok">
<Success>Custom rule(s) installed</Success>
</Response>