You can create a new 3d sketch, click convert entities and click all of the edges of the part and hit ok. This will make all the edges into a new sketch.
You can probably use the Split Line feature to create your path.
Do what Jerry said!!
from a 2d sketch draw the shape, then go to insert curve splitline, selact all fthe faces you want to split then click the green check. oh yeah set the direction to oneway.