Looked into doing just that - very complicated and expensive not to mention the requirement of owning the bike for six months before being allowed to bring it into the country. All the paperwork has to be completed and authorised prior to it leaving the US otherwise you'll have a very expensive paperweight.
In my case it was easier and cheaper to just buy here.
There are a number of companies that specialise in importing bikes (usually HD's) - do a Google search.
Cheers,
A.