Everything I've seen has said otherwise. IEC are not extendable. In order to be eligible for Implied Status, a permit must be extendable. IECs can be renewable - but that isn't the same thing.
Refer to what PMM has said
http://www.canadavisa.com/canada-immigration-discussion-board/implied-status-when-changing-from-worker-to-visitor-t99378.0.html;msg1350056#msg1350056
Read Sweden's post
http://www.canadavisa.com/canada-immigration-discussion-board/updated-topics/-t148829.0.html;topicseen
Refer to what PMM has said
http://www.canadavisa.com/canada-immigration-discussion-board/implied-status-when-changing-from-worker-to-visitor-t99378.0.html;msg1350056#msg1350056
Read Sweden's post
http://www.canadavisa.com/canada-immigration-discussion-board/updated-topics/-t148829.0.html;topicseen