User:Evad37/kmlToJson

KmlToJson (source) converts KML files into GeoJSON. On Template:Attached KML subpages (where KML files are stored), the script adds a "GeoJSON" link near the "Move" link (in the 'More' dropdown menu for Vector skin; a tab in Monobook skin) that does the conversion when clicked. Copy the result and paste into an appropriate subpage of Map data (example: Map data/Wikipedia KML/Iowa Highway 192). The map data can then be used in mapframe maps, e.g. by using maplink's raw parameter:

Installation
To install the script, add the line: importScript('User:Evad37/kmlToJson.js'); // User:Evad37/kmlToJson to Special:MyPage/common.js.