These are already in a format expected by the geolinearray command, so they can be read directly. Normally, one needs only one group. It is distributed from the GMT web site .
Additional arguments select the data, region, and resolution.
Consult the pscoast man page for details. The stream can be adjusted by an intermediary application, whose source code is psc2tkgm.c , which should be straightforward to compile. Many other outline sets and resolutions are available from GMT, as documented in the pscoast man page. GMT is a rather large download. If you have a slow connection, you can also obtain it on the FreeGIS CD .