Several options Matt...
Easiest way is to use one of those silver, gold or white "paint" pens used for writing on plastic, card etc. The make I use are called DecoColor, and as you can guess by the spelling, are from the US. They have a medium nib. No need to prepare the blank, just rub down with a wipe, write, leave for 24 hours and use flexcoat or similar over the top.
For a finer line (smaller text) use a "mapping pen". Its just a fountain pen nip that you dip into white ink or Tamiya Acylic modelling paint. Some people prepare the blank by using a very very fine wire wool to remove the surface gloss to guve the ink something to "bit into", but I dont bother. I just wipe the blank and write. I then seal the letters with colour preserver and then epoxy.
Another way is to use transfer paper in a printer and make a transfer for the rod. You cant get white ink on a normal colour printer though! Apply the transfer (normally a water based one) and then seal with colour preserver and epoxy.
Lastly, use Lettraset transfers and add the words individually, then epoxy.
Hope that all makes sense..