Found it here: http://awesomesql.wordpress.com/2010/02/08/script-to-drop-all-connections-to-a-database/
DECLARE @dbname NVARCHAR(128)
SET @dbname = 'DB name here'
-- db to drop connections
DECLARE @processid INT
SELECT @processid = MIN(spid)
FROM master.dbo.sysprocesses
WHERE dbid = DB_ID(@dbname)
WHILE @processid IS NOT NULL
BEGIN
EXEC ('KILL ' + @processid)
SELECT @processid = MIN(spid)
FROM master.dbo.sysprocesses
WHERE dbid = DB_ID(@dbname)
END