I cannot give you ETA, because now we need to decide how this button should work. I opened a discussion here:
http://forum.x-cart.com/showthread.php?p=370995#post370995
Anyway, I can help you to create a mod that will make this button work precisely as you need. If you want to go for this option, please create an empty module according to the article here:
http://kb.x-cart.com/display/XDD/How+to+create+a+module
Once you are done, please let me know and I will tell you what to do next.