{ INCLUDETEXT "{ MERGEFIELD linktofile }" }

should be enough, but
a. all the {} have to be the field braces you can insert using ctrl-F9
b. you may need to double up all the backslashes in the file names to make
it work (I believe this varies depending on the version of Word and
Windows).
c. Access hyperlink fields probably won't work as they have a format
something like

displaytext#linktext

You can extract the linktext in an Access query - e.g. if the hyperlink
column is called h, your query SQL could be something like

SELECT  Mid(h, instr(1, h, '#') + 1, Len(h) - instr(1,h,'#') - 1) as
hyperurl, * FROM mytable

Other things you may be able to consider are:
 just putting a filename (not a pathname) in the data source, and
hard-coding the rest of the pathname in the document, e.g.

{ INCLUDETEXT "S:\\Forms\\Lease Forms\\lsefrms\\"{ MERGEFIELD
myfilename }" }

or putting all your texts in a single Word file and bookmarking the sections
you need, e.g.

{ INCLUDETEXT "S:\\Forms\\Lease Forms\\lsefrms\\myfile.doc" "{ MERGEFIELD
mybookmarkname }" }

Peter Jamieson