I think you are asking:
how do I get a program to stay resident (system tray programs), listen for a hot-key, and send text as-if from the keyboard when hot-key is pressed.
IF so, build this little by little. First figure out how to spoof the keyboard message, get that working, then wrap it with the resident and hot-key action stuff, research those 2 topics one at a time...
I don't know how to do this anymore. I last did it in like win 98 and hesitate to try to show you now. But there are probably examples on the web; these type programs are fairly high demand by gamers and others.