Can I hook this breakout board up to the thing I want to measure?
According to the Sparkfun web page:


  The ACS712 Low Current Sensor Breakout outputs an analog voltage that
  varies linearly with sensed current. To calibrate, first set the
  output offset to the desired level (with zero current on the sense
  lines, read output with a DVM). Then with a known current input (a
  100mA limited supply works well for this), set the output deflection
  with the gain pot. Sensitivity is then calculated as (Vref -
  Vdeflect)/(current input).


You've done the first part, now do the second part.