Android is designed to do things like that via labelled shortcuts (not blind long-presses on otherwise-unlabelled dialer-number-buttons).
I have home-screen shortcuts to insta-dial my wife and another to jump to her text-message-window (but i'd love a home-screen-button to insta-send a predefined message)
all you have to do is long-press the home screen, select the first option, "shortcuts", select "direct dial" (or for text-messages "direct message") and select your target.
If you end up with too many direct-dial targets, create a home screen folder for them, just be sure to add items in the final order you want them in ... I have not been able to find a simple way to arbitrarily rearrange icons within a folder. (Anyone know an easy way to do this?)