?footnote when no page numb. avilable/on-line source

["Rita Doyle, K-12, Cedar Cliff Local, Cedarville, Ohio"]

We have Trimmer's *A guide to MLA documentation* fourth edition, and Li and
Crane's *Electronic Style*, but have been unable to find a sample footnote that
addresses the lack of page numbers.  The Sr. Eng. teachr has requested students
use line numbers when page number are not available, but when using on-line
services instead of CD-Rom, no line numbers are given either.  Some of these
articles are rather lengthy, and counting lines would be tedious.  However,
being able to specify exact location of a citation would be useful.  Your
comments, ideas, solutions, please.  And Thank you!  Rita