Well, several different ways to do it.
You can buy a small lamp with a "bite" attachment that can just wedge onto any flat surface - I have one attached to a bookcase. The connection between the base and the lamp fixture is flexible, so you can shift it around to get just the right amount of light. This works at a fixed location, of course.
Then, if you do it with a regular hand-held flashlight (ie., not a headlamp), there are two issues: how you hold the flashlight, and which flashlight is best for the purpose.
I find I can kind of wedge the flashlight in the crook of my neck and, if I position myself just right with pillows, it works.
This then narrows down which flashlights you can use! for instance, the old standby, the Inova X5, has plenty of good, floody lumens for the task, but tends to get hot! So somewhat uncomfortable for the old neck...
Alternatively, I use my McGizmo Ti-PD-S, with a Surefire F04 diffuser (which matches the size of the bezel perfectly). The resulting beam is then perfect for reading. (no hotspot, and enough light to illuminate most of a page) On low, the light doesn't get hot. On high, it does get hot, so hopefully the low output would be enough for your eyes.
Actually, the Lumapower M3 with the 2xAA tube works great for the purpose, because it gives a beam that is not too narrow, and the extra tube length helps with positioning. (the light even has, at least theoretically, an adjustable beam/focus, although this feature tends to make a rather small degree of difference in practice). It has 3 different output levels, so you can find one that works. You can also then use NiMH batteries which is a big plus for long hour uses like reading.
A final possibility (which I haven't tested for reasons that will become clear) is just to use a Molle design, so if you can just place the flashlight sitting on a nearby flat surface so it can illuminate the book your holding, it will be great. The reason I haven't really tested this yet is that the only Molle light I have is the Streamlight Survivor, which by design has a very narrow (10 degree) beam and so doesn't work that great for reading. One of Elektrolumens' Angelux designs, which should be very floody, might fit the bill.