I think there is a pts plugin still included with AC3D - see Help->About-plugins.
You can also easily make an AC3D file containing vertices. See near the end of this:
http://www.inivis.com/ac3d/man/ac3dfileformat.html
DXF files can be problematic because of the large number of versions but feel free to send some sample files of the other formats so we can have a look.