For a one-time need? Nah. How about something like this?
bcp "SELECT definition + NCHAR(13) + NCHAR(10) + 'GO' + NCHAR(13) + NCHAR(10) FROM sys.sql_modules sm JOIN sys.procedures p ON sm.object_id = p.object_id JOIN sys.schemas s ON p.schema_id = s.schema_id WHERE sm.definition LIKE '%string your looking for%' AND p.is_ms_shipped = 0;" queryout C:\@\MyCode.sql -w -T -S ServerName -d DatabaseName
Then open the file and replace CREATE PROC with ALTER PROC and do what you need to do with the code.
Edit: changed "NOT LIKE" to "LIKE" since we reversed the approach from subtracting objects to grabbing what we want
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato