It is called "sortilege" (spelling??), and yes the Catholic Church believes it is possible. People can and do make deals with the devil, according to many sources.
Malachi Martin left the priesthood, in the 1970's I believe. I have read his book that he wrote back in the 70's, "Hostage to the Devil". An interesting read. It is written in more of a narrative/story format, and tells the story of 5 or 6 cases of possession (supposedly true, but with the events and people "fictionalized" so that no one will know who he is talking about). He also publishes the entire Catholic Rite of Exorcism in the back of this book. Also very interesting reading (he stresses that only ordained Priests are allowed to perform exorcisms, and then only with the permission of their Bishops).
However, since Martin left the priesthood, some question whether he is a good source to go to on such topics. He also started behaving in a more "eccentric" fashion in his later years, from what I have heard.
One such friend who questioned Martin's orthodoxy suggested that I instead read a French Monsignor who wrote upon the same topic back in the 1950's. His name is Msgr. Leon Cristiani, and my friends maintained that since he remained faithful to his priestly vows, they thought he would be a better source to read. I purchased and read a 1977 translation of one of his 1950's books called "Evidence of Satan in the Modern World" (available on Amazon). Also a very interesting read. This book is shorter than Martin's book, and is not written in as much of a story/drama format.
Msgr. Cristiani is also the one who discusses "sortilege".
I am not sure what to make of Malachi Martin. Some have nothing but praise for him, and others don't think very highly of him.
All of this from the "for what it is worth" department. I am not an expert, but I have read these few books (I have never seen the movie "The Exorcist" - even at my age, the thought of doing so still scares the hoo-hoo out of me!!
: )