abe this is for all three services together (voice access button mapper and mouse)
adb shell settings put secure enabled_accessibility_services com.android.cts.flar2.homebutton/a.i:com.android.cts.apps.accessibility.voiceaccess/com.google.android.apps.accessibility.voiceaccess.JustSpeakService:com.android.cts.appsflipcursor/com.android.cts.appsflipcursor.services.MouseEventService
adb shell settings put secure accessibility_enabled 1