Hi,
In order to give access to the procedure so that the other user can make changes is to .The SYS user should give him ALTER ANY PROCEDURE system privelege.And u as a user should give him EXECUTE PRIVELEGE on the procedure.
If the procedure contains undelying tables in ur schema,then u should also grant him necessaty privliges on the tables to that user.

for e.g.
Say a procedure proc1 is in SCOTT schema.And u want to give him access to make changes to the procedure as well as run that procedure to user A

Step 1)Connect as sys and
grant alter any procedure to A;

Step2)Connect as user SCOTT and
grant execute on proc1 to A;

if the procedure is accessing some tables in SCOTT schema,u have to grant the necessary priveleges on the underlying tables to user A also,

In case of any doubts please be free to ask me at [email protected]

Regards,
Rohit Nirkhe,Oracle DBA,OCP 8i
[email protected]