Power comes into one light fixture and also cable to switch goes down from there.
Run a 3 conductor cable
(14-3 if circuit is 15 amps) from each light fixture (except the first) to the desired switch location.
At each fixture (except the first) disconnect its black wire from the black power wire(s) coming through and connect it to the new black wire down to its switch.
Connect the new red wire to the black power wires passing through.
Connect the new white wire to the bundle of white wires (including that of the fixure).
At the fixture where the power comes in remove the black wire continuing on to the other fixtures from where it was and connect it to the incoming power wire. Whatever else was connected to the incoming power wire stays.
At each new switch box connect the red and black wires to the switch. Put a small wire nut or some tape over the white wire end which remains uncut and unconnected* for now.
*2011 code requires that the neutral go down to the switch box just in case someone wants to extend power from there later.