Hi Brian, try this (requires v5):

function GetTangents( crv, dir )
{
    var params = crv.getTangentsToDir( dir );
    for ( var i = 0; i < params.length; ++i )
    {
	var pt = crv.evaluatePoint( params.item(i) );
	var factory = moi.command.createFactory( 'point' );
	factory.setInput( 0, pt );
	factory.commit();
    }
}

GetTangents( moi.geometryDatabase.getObjects().getCurves().item(0), moi.vectorMath.createPoint(0,0,1) );
GetTangents( moi.geometryDatabase.getObjects().getCurves().item(0), moi.vectorMath.createPoint(0,1,0) );

- Michael