Honda idles are pretty finicky... The only way the idle screw will work is if you have the IACV unplugged. If you try adjusting the idle with it plugged in, the ECU will compensate for the change. Here's what you need to do...
1. Start car and let it warm up.
2. Unplug the IACV (yes, you'll get a CEL)
** It might stall so be preparred to give it some gas...
3. Adjust idle set screw until car is idling at 650 rpm.
4. Turn car off.
5. Plug in IACV and reset ECU to get rid of CEL.
6. Start car and make sure idle is where it needs to be. Go back and repeat if necessary to get desired idle.
*** There are many factors that will not let this procedure work like it should... i.e. leaking gaskets, bad pcv valve, vacuum leaks, tps not properly calibrated, fitv issue, etc...