Trend also make pin chucks and I have one, like Martin said, it can be difficulkt getting a small drill bit into a normal pillar drill. Another way to over come your problem is to drill a series of really small holes along the line of the vein, say 4 or 5 and form a slot, it's a bit time consuming but you can use a really small drill bit for this.
I personally will use a 1mm drill bit and if this is a bit bigger than the vein I just make the vein the same size, even if it is slightly bigger than the vein on the pattern, at the end of the day it does not really matter, it would not be out of place and would still look perfectly natural. It is a problem with some patterns and obviously the person that designed them has not done so with the scroll sawer in mind when it comes to these tiny cuts. I often modify patterns, especially where there is a weak spot.