I know this is an old thread but it is useful info to have.
I recently imported a rifle scope from the States and you have to go through the same hoops for gun parts
Go here to find out the info for what you want to do, download the appropriate .pdf file form and send it away. I was able to fax it to them and have them fax the International Import Certificate directly to the store in the States so they could apply for an import license from their end quicker.
International Importing