CAF have announced the details of the qualifying system. Part of it was already described by Issa Hayatou last week.
Here's the official CAF announcement:
"Countries that do not qualify for the Orange CAN Gabon – Equatorial Guinea 2012 will play a first round eliminatory, with direct elimination, with a view to finding fifteen teams. The period from 15 January 2012 to 15 February 2012 was chosen for this first round.
If necessary, if the number of teams involved exceeds 45, a preliminary round would be organised. In this case, the criteria for the teams to undergo a preliminary round will depend on FIFA ranking.
The second round of qualifiers , also through direct elimination, will witness the fifteen qualified teams of the first round qualifiers to play against the fifteen teams (except Libya, host country of the 2013 edition and by consequence already qualified) that would have participated at the 2012 CAN, after complete draws.
If the Libyan team qualifies for the Orange CAN 2012, the fifteen other teams will directly play the second qualifying round of the 2013 CAN.
If Libya doesn’t qualify for the Orange CAN 2012, Gabon and Equatorial Guinea will play home and away play-off and the winner will participate in the second round qualifiers ."
Gabon and Equatorial Guinea will surely be rooting for Libya to qualify for the 2012 finals.