One option you might consider is using the OUTPUT clause available in SQL 2005 and later. Of course, without knowing the details ofhow the sequential numbers are generated or stored, this is only a guess on my part.
Here is a simple example - you can capture the value that is output and send it to the client.
CREATE TABLE #tmp(id INT);
INSERT INTO #tmp
SET id = id+1
DROP TABLE #tmp;
-- "If a book is well written, I always find it too short"