This is how my item definition looks like:
String RFLinkRaw "RFLink raw data [%s]" <text> { serial="/dev/ttyUSB0@57600,REGEX(([^\"\\r\\n]*[\\S]))" }
Serial binding allows the usage of a regex in the item definition. Took me quite a while to find out this is being treated as a string - therefore the backslash has to be repeated before r / n / S.