Conference papers can be tricky (many of these aren't available online).
Try the library catalog for the conference itself - use keyword searching from the unique words in the conference, but leave out things like "3rd" or "twelfth."
If you cannot locate a conference proceeding in the library's online catalog, give the reference desk a call at 713-348-5113 to talk with a reference librarian.
Or, you can always submit the info you have to the interlibrary borrowing department (using the ILLiad system; current Rice faculty, students & staff only) and we will do our best to find you a copy of the paper you need.