Custom modes are integrated with Intel HD Graphics Control Panel on the latest drivers and a separate Custom Modes App is no longer needed. You can access Custom Resolutions by opening the Intel HD Graphics Control Panel, click the Display tile, click the Display dropdown and select Custom Resolutions.
Have same problem but "Custom Resolutions" does not appear in that dropdown "display" list for me. Only the first 2 options Help?
Is your problem resolved/figured out? Custom Resolutions can be found either in older drivers with older versions of CUI using the CustomModeApp or in more recent CUI versions it is built into the CUI.