Nightfly,

I've seen at least two different versions of Formulas that differ in the axle hardware. On one version, there's a 4-5 mm spacer on each side that you can ditch and presto, you have 110 mm. On the other, there's nothing to remove that isn't irreplaceable. But you can get replacement generic parts that are thinner from Bicycle Research (any good shop will have a parts box from them) and use them instead. This takes care of the actual spacing. Then you can either file the axle or file the stay end to get the 8 mm flats. Note that it's harder than it looks to file opposing sides of an axle with decent flats, so I recommend doing the stay ends instead.

And by the way, to another comment above, no matter how much you try to orient a flatted 110 axle in a pair of stay ends with 10 mm slots, it won't want to stay there. It tends to creep while tightening and you end up with a hub that's difficult to align in the slots. If you go to 110, plan to commit to matching stay ends and axles. Again, another reason to file out the frame and be done with it.

The milling that Tanabe-san did above is hard to do properly without a proper jig, such as you see mounted on top of the stay-end. I wouldn't suggest that you can do it easily or accurately without much more effort than it's worth, and this is not a jig that a local framebuilder is likely to have -- it's a unique thing that keirin frame builders construct for themselves.