I’ve never seen this subject brought up before, but there’s an area of the Hoekje/Kosel Spreadsheet that addresses cross-fingerings.
I’m no rocket scientist, and I can get a very nicely tuned tube from the main calculations, and can also be certain that the local cutoff frequency won’t be too low for any given tone hole.
The cross-fingerings section of the spreadsheet seems pretty straight forward, but there’s not enough information provided to make the light bulb switch on over my head… but maybe I’m just a slow learner! 
It’s not too difficult to get the one really important cross-fingering right (C-nat on D whistles), but it does require a few trial and error attempts that I’d rather avoid if possible… and it would really be nice to calculate some of the more difficllt cross-fingerings from the comfort of my computer desk! 
Would someone be so kind as to enlighten me regarding this area of the spreadsheet?
Where would we find this data?
Here (http://www.bw.edu/~phoekje/acoustics/Flutexl4.xls) is the original version with all the measurements in centimeters.
Here (http://www.cwo.com/~ph_kosel/dflute.zip) is the modified version with all the measurements converted to inches.
As you can see in the spreadsheet, several reiterrations are performed to calculate true position of the toneholes with adjustments made for the area created by other toneholes.
Also, the Closed hole correction is missing in the spreadsheet. This is not hard add though. It won’t make a big difference in metal tinwhistles that have little chimney height. It will make a difference in thick PVC or wood however.
You can add as many cross-fingering combinations as you wish.
The values under 2S in cross-fingering table are the extra toneholes that are cover under the last open tonehole. In the Ab example, the third hole from the bottom is open and then the 2S values of the remaining two holes are added for the cross-fingering compensation. This is explained in detail in A.H. Benades books, “Fundamentals of Musical Acoustics” on page 452.