Hi PlasmaFX - there is not currently any regular way set up to do that in MoI, it is something that I want to add to an extended object properties dialog in the future.

But it is possible to set up a script that will calculate the length of the selected curves and copy that text to the Windows clipboard so that you can then paste it in somewhere to see what it is - will that "quick & dirty" method work for you?

If so then see here for the script, you set it on a keyboard shortcut:
http://kyticka.webzdarma.cz/3d/moi/#CurveLength

- Michael