How to map Cura printspace to Prusa I3 printspace
Well, in my particular case, it helps to have the X and Y control (motor and endstop switch) plugged in to the correct ports :-( .  That took care of the X vs. Y orientation problem.

If you command "Home All" either via the LCD panel or over USB, the nozzle should sit in the front left corner of the bed as you face the machine ("stage right" for you thespians). 
The link Chris T provided, ultimaker, provides helpful background information as well.

Next, if there are small offsets, find control can be set with a script similar to the following (leave out the auto-levelling command if you don't have that),
from printerbot talk forum .

M104 S{print_temperature}
G21 ;metric values
G90 ;absolute positioning
M82 ;set extruder to absolute mode
M107 ;start with the fan off
G28 X0 Y0 ;move X/Y to min endstops
G28 Z0 ;move Z to min endstops
M109 S{print_temperature} ;wait on temperature line
G29 ; Auto bed levelling
;G28 X0 Y0 ;move X/Y to min endstops
G92 X132.4 Y20; Reset actual position after G29 bug
G92 E0 ;zero the extruded length
G1 F{travel_speed}


And finally, there's a calibration file at thingiverse which prints large squares so you can see the exact offset.  I hope to get that file modded with a couple markers (indents, e.g.) to verify orientation as well as location.