Have a look at this on youtube <http://www.youtube.com/watch?v=3fUxQgGpdFM> it's flame polishing a duck call, I know it is bigger than your pen top, but worth a look.
I have just looked on ebay and saw this torch which is cheap and small. I bought one just to try so will let you know if it will get into a small hole easily. <http://www.ebay.co.uk/itm/Pencil-Butane-Soldering-Iron-Mini-Micro-Refillable-Blow-Torch-/230850553248?pt=UK_Home_Garden_PowerTools_SM&hash=item35bfc3e5a0>
Peter