This pen requires no soldering and little electronics knowledge!
http://www.wiimoteproject.com
http://bloglearningrhhs.blogspot.com
Parts:
Energizer LED2BU1 - http://au.farnell.com/1110816/electrical-circuit-protection/product.us0?sku=eveready-led2bu1
(also available in any Coles or Woolworths)
Vishay TSAL6400 IR-Led - http://au.farnell.com/3152868/optoelectronics/product.us0?sku=vishay-tsal6400
18ohm Resistor - http://au.farnell.com/1462380/passives/product.us0?sku=ohmite-oy180ke (cheaper: http://www.dse.com.au/cgi-bin/dse.storefront/4881e77303a1a1102741c0a87f9c0744/Product/View/R1632) Less