set shellcmd to "/path/to/your/binary/rebuild_services"

display dialog "Are you sure you want to rebuild your services menu?" ¬
     buttons {"Cancel", "OK"} default button 2
-- ¬ is a line wrap. 

set the reply to the button returned of the result
if the reply is not "OK" then exit repeat

with timeout of 1000000 seconds
	try
		set output to do shell script shellcmd
	on error errormsg
		display dialog errormsg --in case anything goes wrong
	end try
end timeout

activate me
display dialog output