Added this to our feature list.
This is currently possible. Just long press on the map and it will drop a pin. Then tap the pin callout and choose "Create as Waypoint". You can also drag the pin to move it, or fine tune the coords in the create dialog.
This is something we have had on our feature list for a while and hope to get it added very soon.
Others have suggested this as well. So an automatic "dip" list?
