CBP Response:
An arriving alien may request issuance of a paper Form I-94 when applying for admission at Customs. The alien will then be referred to Secondary Inspection to be issued a paper Form I-94. The alien may be delayed depending upon the workload in Secondary Inspection as Primary Inspection officers do not issue paper Forms I-94.
source: CBP/AILA Southern California Chapter Liaison Meeting September 24, 2013