Is there anyway to embed (customise) the icon for a particular Word document?

I have created a library of Word document templates for use by members of my work team. I want to make it as easy to use as possible which as why I want to customise the icons for each template eg report template, work request template etc. Now I know that you can edit the icons for Windows but these are controlled by a icon -> Document types mapping. I understand that it is possible to embed icons into a particular file to overide the WIndows default. Photoshop for example enables you to create a thumbnail of that file's image contents. Does anyone know of a freeware utility (preferrably) that can edit a file (not file type) icon?