It can be done, but, you need to use one of the other template modes. The following should work:
Code:
{title:'re(re($,' ',.),'\,','')'}_{authors:re( ,.)}/{title:'re(re($,' ',.),'\,','')'}_{authors:re( ,.)}
This is in template program mode. I usually do things like this in the general program mode, but you had half of it, so I kept going that way.