No, they aren't; they don't have a suitable API. So you have a few other options, presented in no particular order:
- Use DNS manual mode--it will work with any DNS host that lets you set TXT records for your domains, but will require you to manually do so at least every three months in order to renew your certificate.
- Move your DNS service to another provider--Cloudflare is one that's free and works fine with the Acme package (it's what I'm using), but there are a number of providers available.
- Come up with a way to do HTTP validation instead. For this to work, Let's Encrypt will have to be able to connect to http://yourfqdn/.well-known/acme-challenge, and you'll need to be able to put a small text file there for them to read. This blog post addresses one way of doing this (it's the third hit on the google search I suggested above).