Selecting odd vs. even curves to extrude consecutively

Hi,

I'm have a series of section profiles that are being extruded and I wish to extrude every other profile. If the the profiles are on points 1 through 10;

I would like Extrusion Set 1 to be between points [1-2],[5-6],[9-10]

Extrusion Set 2 to be between points [3-4],[7-8].

I have been trying to cull the extrusion list but it isn't being done in order. Also, dispatch is only separating closed curves from open curves so that hasn't worked properly either.

Any chance someone can help?

Thanks