Forms Data Controls :: ListView Edit And Insert Template, Add Pop Up Button?

I have a ListView Which displays Customer, product, price, Quantity and comments from database.The User can either edit it or Insert new items. In Edit Item template and Insert item template, i need to add a image button next to the textbox, which when clicked, will display a pop up window with list of customers or products.I have been doing it with the normal aspx page with textboxes. I use click handler to pop up the windows.i'm not able to do with listview Please help to give a solution to it.How else can i add an image icon and click it and get the values back to the textboxes?i will post what i'm doing without listview first and then the part of the relavant code of Listview.