Yep: in the tck2connectome help page, check out the options for the connectivity metric, as well as the -stat_edge option (note that the command interface here changed as part of the last tagged update).
So, for instance, if you want the mean streamline length in each edge:
- Use
-scale_length: This makes the contribution of each streamline to the relevant edge equal to the length of that streamline, rather than unity. - Use
-stat_edge mean: This takes the value of each edge as the mean of the values contributed by each streamline within that edge, rather than their sum.
“Calculate the lengths, take the mean” = mean length 
It’s not as immediately obvious as the old interface, but it’s a lot more flexible.
Have fun!
Rob