8 pints,

My tuner is a Seiko chromatic tuner which will automatically detect the note being played and the octave (though the octave is not displayed). There is also a little dial which has a range of -50 cents to +50 cents. To tune to equal temperament (ET) you get the pointer on the dial to zero. If you want to tune to other temperaments, you need to find out how many cents sharp or flat relative to ET you need to tune.

Assuming your tuner is similar, you need to tune your fiddle strings as follows (all figures relative to equal temperament);

Scottish Small Pipes (A=440 Hz)

     4G    198    Hz  18 cents sharp
     3D    293.33 Hz  2  cents flat
     2A    440    Hz  0
     1E    660    Hz  2  cents sharp
  

Northumbrian Small Pipes (F=353.38 Hz)

     4G    198.78 Hz   4 cents sharp
     3D    294.48 Hz  16 cents flat
     2A    441.73 Hz  14 cents flat
     1E    662.59 Hz  12 cents flat
  

If you want the formula to work this out, PM me.

In practice, most people are will probably not notice to +/- 5 cents, but there are a few with very fine perception who can detect very small differences in tuning. On my tuner the precision on the "dial" (it is generated on an LCD screen) is no better than +/- 5 cents so you really need to use your ear for the final fine tuning.

At the end of the day, your ear must be the judge.