which part are you having issues implementing? The packet explanation from XEP-0234 is pretty straight forward on how the communication needs to happen.
if you read there is a spot where it mentions the type of bytestream it is using to transfer the data: SOCKS5 Bytestreams
if you are asking from a code impl standpoint - that will vary depending on how you have built your clients of course. From the XMPP standpoint it looks like some very generic packets to establish that there will indeed be a file transfer happening and then you handle the transfer using a bytestream between the two clients.
The linked article above covers this in much more detail. cheers