Stephen Seifert does indeed have a multi-part tutorial on how to set up TablEdit for dulcimer and also how to make all kinds of fancy adjustments. It used to be available for free on his website. Now he has it posted at the Dulcimer School, which is a subscription site where you pay per month. It might be worth joining for one month just to access the TablEdit tutorial. It helped me out a lot and I still go back there periodically when I can't figure something out. TablEdit is very powerful but not very instinctive. It takes a while before you can work with it really proficiently.
I did a workshop on using the 1+ fret with Karen Mueller a few years ago at the Redwood Dulcimer Day. I was the only one who had a dulcimer with a 1+ fret, but she pretty quickly taped paper clips to everyone else's for the purpose of the workshop. I think she just eyeballed it around halfway between the 1st and 2nd frets for the purposes of the workshop, but if you were doing this for a gig or for a more permanent solution, you would want to use a fret spacing calculator or template and measure the exact placement.