The booklet, Free File Fillable Forms FAQs and Limitations, January 8, 2013, under "Where do I locate Form 4562," states
Form 4562 is not available from the "View/Add Forms" menu .... If you are filing Schedule E, select the "add" button for Form 4562 on line 18 of Schedule E.
Line 18, however, says only "See Form 4562." I see no "add" button.
I emailed the help desk (irs.gov.websitehelpdesk@speedymail.com) this morning, but no response yet.