Your NiCad batteries will likely have a terminal voltage (fully charged) of 20.8 V. This is 13 cells in series.
You should NOT set your power supply to 24 V as this will severely overcharge the batteries.
Set your power supply to 20.5 V (there are other complexities such as temperature and voltage drop on charge, but I'll ignore them for the moment).
Set your current sense OC/CC to around 120 mA (as WhatRoughBeast suggested).
When you connect a discharged pack the OC/CC will trip and reduce the voltage.
When the terminal voltage of the pack approaches 20.5 V the current will reduce to a trickle.
Under these conditions the pack will NEVER fully charge, and to explain that here is the typical charge graph for a single NiCad cell:
Notice that to get to 100% charge you have to manage a terminal voltage DROP as the battery approaches fully charged.
Using your simple power supply charging, we need to stay on the left of the peak.
I've said above to use 20.5 V, this represents about 1.6 V per cell in your pack. At this terminal voltage you can expect to be about 75% charged. You could select any voltage between about 20 V and 20.5 V to get reasonably consistent results with little chance of damaging your pack.
You could also of course build yourself a simple charge controller to connect to your power supply and get closer to 100% charge ...however that's possibly not in your DIY capability.
For example, this might be all you need:
simulate this circuit – Schematic created using CircuitLab