to
indeed does the trick, and it is pretty trivial to use:
scala> val l = List(1,2,3)
l: List[Int] = List(1, 2, 3)
scala> l.to[ListBuffer]
res1: scala.collection.mutable.ListBuffer[Int] = ListBuffer(1, 2, 3)
Works in scala 2.10.x
For scala 2.9.x, you can do:
scala> ListBuffer.empty ++= l
res1: scala.collection.mutable.ListBuffer[Int] = ListBuffer(1, 2, 3)