1. An apparatus for implementing conditional packet alterations based upon a transmit port comprising: a selection mechanism for implementing the packet alterations; said selection mechanism including an indirect data array for storing packet alteration data; a multiplexer having inputs respectively sequentially receiving one or more select entries of a sequence of frame alteration instructions and transmit port numbers associated with a packet being transmitted; said frame alteration instructions having a predefined instruction format including a select field including a select flag, an entry select; and a byte select; and a multiplexer select input receiving a selection control from said sequence of said frame alteration instructions; and said multiplexer providing a sequential multiplexer selection from said inputs responsive to said selection control; selection logic coupled between said multiplexer and said indirect data array; said selection logic for generating a data array select input using a sequential multiplexer selection and said sequence of said frame alteration instructions; and said data array select input being applied to said indirect data array for selecting packet alteration data from the indirect data array for the packet being transmitted; and dataflow assist hardware for transmitting said packet from each respective transmit port for said plurality of said transmit port numbers, responsive to said selection logic performing said alterations.