Not exact (depends on what other files are affected than .2da files) but
1) install USM
2) install TSLRCM
3) install TSLRCM / USM Patch
4) install Greatsabres using stoffe's 2da Converter/Merger Tool (
http://www.starwarsknights.com/tools.php#gmt) on ALL .2das the mods share.
The TSLRCM patch should shoulder most of the burden of USM / TSLRCM shared .2das. Using the merger tool "hopefully" would combine the .2das that TSLRCM / Greatsabres adds so there's little to no conflict. (if any)
Haven't played the mods enough to know what all is affected (USM aside).. but that would be the "basic" route.
Any additions or corrections are most certainly welcomed :D