Open beta implies bugs and issues that still need to be overcome. You have many options and I’ll list them:
- I keep an active list of hosting who support lets encrypt on shared hosting if you wanted to change host providers.
- Follow the guide using a linux livecd like linux mint and create your certs (in virtualbox) and doing this 4 times a year is extremely easy: Tutorial for OS X local certificates and Shared Hosting
- Bug your hosting to add support via social networking or their feedback email, they probably dont know about it.
And above all, vote this up: https://features.cpanel.net/topic/provide-support-for-lets-encrypt-automated-certificate-management-ssl
Sooner a legit cpanel addon is made, faster it gets implemented.