Be sure that you separate these two tasks in your mind. The eConnect piece is totally separate from the design piece.
I'll skip the eConnect part, that should be covered on that forum anyway. The challenge is how to open that form. I have code to open the Sale Transaction Entry (STE) form here http://vstoolsforum.com/forums/p/63/121.aspx#121, but we have to have some place to put that code.
You also have to have some place to initiate the import from.
Could we have the use open the STE form and push a button to do the import, that button would open up a custom form and from there we could do the import? Then when the form closes we could navigate the STE form to the new doc?