Linking to images

I have a friend and they have asked me to help them on a project of theirs. As he photographs birds he has made a list in Microsoft word of all the birds, which he has photographed. What he would like to do is attach a link to the file so when you click on it it would open up/direct you to the image. For instance opening that image up in iPhoto or preview. Since he has most of his photos arranged in iPhoto is there any easy ways if anyways at all of doing this?