The only extra stuff that you might need will be the length/ encoding required by the ISO-8583 variant you are implementing. Secondly, once you know the encoding itself, it's just a matter of putting all tags together one after another and you get your DE 55-no delimiters and no meta information it's as simple as that. Well, firstly, one needs to know that EMV tags are BER-TLV encoded in Field 55.
DE 55, also called Field 55, in ISO-8583 is Integrated Chip Data so, it's easy to deduce that the EMV tags of an online transaction should be put in DE 55 when creating the corresponding ISO-8583 financial transaction message.
