You can, interstate was doing that but removed for release afaik, Use the gui functions
Why did they remove it?
Since interstate is my gamemode, i think i can answer this
Before the release, interstate suffered some major, strange issues, which forced me to strip out all 'unnecesary' things, such as the custom nametags.
To be really honest, interstate was completly rewritten 1 week before release (which is why some things previously seen in pictures and videos might not be there today), so stripping things out was the only thing i had time for.
The code for the nametags is still there, but its very unfinished and shouldnt be used as-is.
I will probably re-add them at a later stage (alongside alot of other things).