Are you talking about cubemain.txt? Here's what I did:Of course first column is any name, then enabled is 1, then version is 100, then numinputs to the no. you want, then item 1, and so on. On the outputitem column, just put "useitem". Don't add modifiers because the item's gonna change stats.
You don't need to set anything in lvl, ilvl, plvl, but be sure to put zero at term column.
Then for the modifiers column, mod 1 put skill then don't put anything in mod1chance, to make sure the item always has the mod. Then mod1param put in the number of the skill you want to use. The numbers are in skills.txt I guess. Then put in mod1min any number from 1 to 30, and then in mod1max any number from 1 to 30 as well. Just be sure the mod1min is less than or equal to your mod1max. That should do it.
Try it and hope it helps. 