Hi, Look at OPENQUERY() in the SQL server BOL, second topic (T-SQL reference)
If you have the linked server set up, you should be able to call the sproc using ORACLE's syntax (whatever that is)
Select * from OPENQUERY(OracleServer,'EXECUTE somestoredprocedure (someparameter) ')
Never tried it, so I don't know if it will work, but you might give it a shot.
Good luck,
jg