Using the shortcut created by the new installer would be good because it will point to launchpad.exe.
The question about the location of launchpad.exe is important. In a clean install, there will be one copy of launchpad.exe and it will be in the EQII directory. In an upgrade install, there will be a copy of launchpad.exe in the EQII directory, but there may be other copies left over elsewhere. It is essential to be sure your shortcut points to the right one. It is better to find and delete those extra copies.
Landlin, I sympathize with your frustrations. SOE could support the mod community better, but at least I still get enough help from them to keep up my testing work for ProfitUI (and EQ2Maps as I can).
LP4 is a big improvement (and long overdue,) but the new launcher architecture has caused temporary issues while people with older installations clean up their setups. Since I understand the new setup pretty well now, I can usually help out.
-= Therendil =-