With ShinobiCharts for Andoird, the Crosshair can only be shown by performing a long press gesture and the length of a long press is taken from the Android defaults. There is no way to redefine this through our API (and as far as I'm aware no way through the Android framework either, though I may be wrong!).
At present the Crosshair cannot be programmatically shown but I can see how this feature would help your use case (you could then potentially use our OnGestureListener() to programmatically show the crosshair when a single touch event occurs). We're always interested in feedback from our users and prioritise feature development based on customer demand. As such I will certainly make a note of your requirement for this though I cannot give any guarantees as to if and when this would be added to our library.
I'm sorry I can't be of more help!