IRULE: Find and Replace Delimiters

I have an i-rule where I grab a variable that is set by APM and insert it as a header, so I can pass it back to the back-end application. We have a case where this variable can contain several pieces of information delimited by ^ and I need to replace those with commas before I send it back to the server. Does anyone know how to do a replace of the delimiters. Thanks in advance for any help you guys can provide.