Hey,
It is possible to fly to Nepal with kayaks, every time we go to England we bring one back with us.
The easiest airlines to use are Jet or Kingfisher. Just madke sure you ring them before and tell them and it should be no issue. I have only ever been charged extra once.
(Kingfisher give you more weigh allowance so they may be better)
Otherwise you can always hire baots in Nepal, we have several you are welcome to use!
If you need any more info on Nepal, feel free to email me on [mail address protected from spambots with javascript] and I will be happy to help.
Oh and make sure you wrap your paddle up well as they are very carfeul with them!