The easiest way to find the film is to go the Family Search catalog and search for the film, number 0017023. This will take you to the collection that includes this film, church records for Our Lady of Guadalupe in Taos. Scroll through the list to the film number. The icons at the right side will tell you if the film is only film, or digitized, and if searchable. If you are checking from home, the presence of a key will indicate restrictions, if any, for viewing the film. Since your citation has a page number, the record should be easy to find (I found it, and it was easy to find). The record is in Spanish.
WHen you scroll through the list click on the camera icon, this will take you to the film. Then, go through the film looking for the volume (book 49) and page (actually folio) number (91). If it is not on the stated page, look at the pages before and after the stated number. The records in a volume should be in chronological order (if the book is in bad shape the pages could be out of order).
BTW: you will need a Family Search account, but it is free; you just need to register.