Hi Peter,
you can achieve the above with multiple ways. you can create search rule and choose below patamters:
pattern type: regex or exact (if you want exact search only)
pattern string: @ for exact match or use (.*) for wildcard match
Pattern behaviour: Replace
Replace string: \1@
source : Any
protocol: Any
target: vcs control
on succesfull match : stop
state: enabled.
Rgds
Alok