Delphi 7 how to fill Body

[mina70]

Hi,
how to set a json body with "GET" method?

MyToken := Dm.RestClient
.Resource('http://.../GenToken')
.Accept(RestUtils.MediaType_Json)
.Get();

I want to send this json string parameter at the body to the server (with above request)?
{"username": "admin","password": "adminpass"}

thanks