This
might help.
If not, I believe you can run a new query on the existing connection, copy and paste the text from the .sql file and run the query.
The last I've used was SQL Server 2005, I'm not sure what they've changed in 2008.
you could also try renaming the .sql file to a .txt file and see if that'll import. - you might have to change some of the syntax tho.