the IDE cable is the one you connect from the mobo to a hdd or optical drive.
If your IDE cables have 3 connectors, [one for mobo-blue, one for MASTER usually hdd BLACK, and a SLAVE connector] then you can connect the optical drive to the same cable.
make sure you change the jumper on the back of the drives to suit.
One MASTER, and/or one SLAVE on each cable.
on the primary channel, [sometimes IDE0, then the bootable hdd is MASTER]