I contacted them, this is the reply I got:
Dear
Thank you for reaching out to our not-for-profit membership association "Dignitas – To live with dignity – To die with dignity" (abbrv: "Dignitas").
We are sorry to hear of your health situation.
Please read our general information brochure, full text available on the site linked hereafter; at the beginning there is additionally a link to a pdf-file so it can be downloaded and printed-at-home:
http://www.dignitas.ch/index.php?option=com_content&view=article&id=22&Itemid=5&lang=en. This brochure contains the basic information as to becoming a member, and information relevant as to requesting the preparation of a physician-supported accompanied suicide (voluntary assisted dying / medical aid in dying) with Dignitas.
Apart from this, everything relevant from and about Dignitas is on our website
http://www.dignitas.ch/index.php?lang=en.
Note, since you live in Texas: there is no assisted dying law (yet, unfortunately), but our colleagues of the relevant local organization which you might like to additionally reach out to:
https://texasdeathwithdignity.org
Wishing you all the bet for now,
Yours sincerely,
The Dignitas team