bitesms

BiteSMS is a different app so you cant acces it from the offical Message app. You could probably SSH into your phone and replace the icon image for it though, or maybe theres even a cydia package that does something similar.

 

the best thing to do is make bitesms your primary text app. then use sbsettings to hide the messages icon. and put the bite icon where your messages icon was

 

After you hide the default SMS app like someone said above, if you want to change the look of the bitesms icon you can do so with winterboard. Just go into cydia and do a search for bitesms, it will come back with many icon choices.

Couple of my favorites are, bitesms no pink retina or bitesms blackretina.