Lots of 2d vector programs have the feature you talk about and it might be worth it if you have to do it often.

Expression 3.3 is still available for free and can be downloaded here:
http://download.microsoft.com/download/a/5/d/a5d625a5-2e3d-4e9c-8608-6de48d7b569f/CreatureHouseExpression3_3.exe

You can export a Ai file from Moi2d and open it with expression.
Selecting the two path and then click on Object/Blend Paths in the menu.


Expression 3 had also an incredible effects line engine.
It's very sad developers had left the direction it was going.


Marc