How to set up REST parameters using multipart-form data in peoplesoft.

We have a requirement to send CSV to third party through REST. The third party vendor has a rest api post service for sending the csv file. The service uses multipart/form-data and needs to have parameters in body as structured. With peoplesoft IB I have used GetAttachment and SetAttachment property to set the csv file properties. The csv headers have to be sent in REST body. How can I specify the body parameters in structured format in peoplesoft ?

The request sample shared by vendor shows the parameters divided in boundaries i.e. before each csv header there is a boundary defined in the request. How can this be accomplished through peoplesoft?