What can I use for temporary wiring harness?
Various sorts of 0.1in header sockets on leads are available, e.g. http://www.adafruit.com/products/266 , which you can just plug onto pins and component leads. Obviously they don't really clamp with any firmness, so you need to mechanically mount everything firmly and maybe add a bit of tape or hot glue to connectors that may be subject to vibration.