Getting the right ham is more important than the beer in my opinion. Go to a good meat vendor and get something bone in if you can, and uncooked but cured. If you slice it and it's homogenous and comes off as a slab, you've failed. If you can pull it apart as shreds of muscle fiber, that's what you want. If you buy presliced or spiral cut, I will punch you in the throat if we ever meet. The hard part with using beer in ham if you really want the flavor is getting the flavor throughout (which a spiral slice would do... but again, throat punch). A smaller cottage ham may work well as you'll have greater surface area to volume.
You could also make a reduction sauce to serve with the ham as an additional way to get beer flavor into the dish besides the brining. When doing reductions, avoid beers with high hop or roast malt character, as those will be intensified as you reduce (at least hop bitterness and roast, hop aroma and flavor will obviously be lost). I think the Scottish would do well.
