As other people have said, start off with each stored proc in a separated text file that is under source control. Write a script that deletes all you stored procedures then re-creates them from the text files (while logging/reporting any errors) – this script should be easy to run. Then every time you update from source control rerun the script. All edits to stored procedures should be done to the text file, not the “live” copy on your local database otherwise you will loose changes when you do a update.
You will soon want someway of auditing your database schema and creating upgrade scripts etc.
If you are only using SQL server then consider SQL Compare from Reg-Gate. I think it will compare stored procs (and other sql) in a text file with what is in your database and sync the two. So letting you use the editing tools in SqlServer to edit the live stored procedures.
(As of the end of 2009, Red-Gate is just about to ship Sql Compare for Oracle)
I have been told that ApexSQL's Diff tool is another option instead of Sql Compare, ApexSQL's Edit claims to provide source control integration.
At the high-end consider Visual Studio Team System Database Edition, however it costs a lot, then you may have to pay even more for Oracle support from a 3rd party. But if you are a Microsoft partner (or can become one) you may get some copes very cheaply.
See also Do you source control your databases? on StackOverflow for a good set of answers on the bigger problem.