Hi Nick,
This is based on a .lst file I was originally given, I think by Olivier Thizy when he was at Shelyak, containing emission lines which are present in the Ar/Ne calibration lamp which they supply.
To use it with ISIS you select file mode in the General tab, type the .lst file name in the box, and then on the Calibration tab you specify the wavelength of one of the lines in the calibration lamp spectrum in the “X coordinate of line at wavelength” box. I use the line at 5852.488 A which in my calibration lamp spectrum is the brightest line close to the middle of the spectrum. Then place the cursor over the centre of that line in the display of the lamp spectrum below and double click. ISIS then fills in the X coordinate of that line in the adjacent orange coloured box. When you then hit “Go” it should correctly identify the location of all the other lines in the .lst file and wavelength calibrate your spectrum.
If you still have problems email me off list and I will try to help further.
David