HOWTO send keystrokes to X app

[Jeffrey Chimene <jeff@grandadventuresranch.com>]

Hi,

I have a data entry application that can accept bar code data. I have 
the barcodes and ASCII equivalents, but no barcode reader.

I think I can use xmodmap to assign a series of keycodes to a specific key.
For example, I'd like to assign KP_1/1 to the string "SQ5029" and KP_1/2 
to the string "SQ5030"

Can someone supply a few xmodmap lines to get me started, or is xmodmap 
the wrong tool?

Cheers,
jec