Which version of Android are you targeting?
You may want to look at http://support.google.com/nexus/bin/answer.py?hl=en&answer=2692469 for the Android 4.1+.
Basically, Talkback will replace many of the gestures, but on some versions of Android you can adjust these by going to
Settings > Accessibility > TalkBack > Settings > Manage shortcut gestures.
So it would make sense to just accept the values that are already supported, and not try to get around it.
Also, you didn't mention if the users are using Explore Touch (http://support.google.com/nexus/bin/answer.py?hl=en&answer=2692788)
If you want to catch these, it appears that you can use onHoverEvent
according to this question:
How can I maintain a one pointer gesture when explore-by-touch is enabled?
UPDATE:
You can look at this question on how to tell if Talkback is active:
How to check if Talkback is active in JellyBean
If it is on, tell the user they need to turn it off for your program to work, perhaps.