Yes, it is offline now. It's a pity.
This evening I've found something I've been waiting for a long time. It is "A Beginning Course in Salish & Pend d'Oreille Dialect Language Curriculum
", an adaptation of the "Nsəlxcin (Okanagan) Curriculum Project" and "Kalispel Language Curriculum". It is here:https://sites.google.com/site/salishlanguage/home
The course is composed of three books. At the moment, only the first book (lessons 1-45) is downloadable. I hope the other two will be downloadable soon!!
Unfortunately, this course uses an alphabet which doesn't include the sounds ʕ (pharingeal), ʕʷ (pharingeal with rounded lips), ʔʕ (glottalized pharingeal!!), ʔʕʷ (glottalized pharingeal with rounded lips) and ə (schwa), which are part of the phonetic inventory of these two languages, as well as of that of Kalispel and Spokane, which are very close to them. Anyway, it is an important publication!
The Salish language is also known as Bitterrot Salish, but natives uses the name Seliš. The Pend d'Oreille has some traits which are closer to Kalispel. The Salish and Pend d'Oreille languages can also be called Montana Salish.