You can set to lead acid type battery, and in the lead acid battery settings set your voltages, and disable equalization. See the section in the manual on the lead acid battery settings, page 22 of the current version of the manual.No, under lithium or a custom setting.
I've got tesla batteries. I'm using them in two different setups currently.
For my 6500ex setup I can set the proper voltages (for my battery). The standard setup voltage is too high.
Can't find anything in the 6000xp manual that specifically shows a custom option.