Currently, installation of the SSL certificate in WordPress using Let's Encrypt is done manually, but I expect that within a reasonable amount of time that a simple installer or install program will become available for those who don't want to hassle with entering line commands in a specific sequence.

Adding Free SSL Certificates to WordPress with Let’s Encrypt
By Jenni McKinnon
WordPress Development
Feb 17, 2016
http://bit.ly/1T2b6C9

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Installing an SSL certificate on your domain is one of the best steps you can take to secure your WordPress site and now with Let’s Encrypt, you can get one for free.

An SSL certificate encrypts the connection between your site and your visitors’ browser so hackers can’t intercept and steal personal information. Normally, SSL certificates can be cumbersome to install and can get expensive, but this is changing fast.

Let’s Encrypt is a new open source certificate authority that’s backed by top companies including Automattic, the folks behind WordPress, as well as Facebook, Mozilla, Chrome, Cisco and Sucuri. The aim of the project is to make installing SSL certificates automated and free for everyone.

These open source certificates are still in public beta and you can expect many changes in the official release, but the current version is stable enough for you to try on production sites.