Maybe an easier way is to create a github.com account, put put your hosts.txt there and add it pfBlockerNg DNSBL list.
Been a while since I last looked a pfSense, not sure if it can access a local file from pfBlockerNg DNSBL, but you try SSHing or log in locally into your box, see if you can create a myhosts.txt under /var/db/pfblockerng/deny/ or something, then add it to your DNSBL lists...