I installed the latest version of FSUIPC. 

I brought up the RUN and entered: %AppData%\Microsoft\FSX\dll.xml.

That gave me this:


<?xml version="1.0" encoding="WINDOWS-1252"?>

-<SimBase.Document version="1,0" Type="Launch">

<Descr>Launch</Descr>

<Filename>dll.xml</Filename>

<Disabled>False</Disabled>

<Launch.ManualLoad>False</Launch.ManualLoad>


-<Launch.Addon>

<Name>Object Placement Tool</Name>

<Disabled>True</Disabled>

<ManualLoad>False</ManualLoad>

<Path>..\Microsoft Flight Simulator X SDK\SDK\Mission Creation Kit\object_placement.dll</Path>

</Launch.Addon>


-<Launch.Addon>

<Name>Traffic Toolbox</Name>

<Disabled>True</Disabled>

<ManualLoad>False</ManualLoad>

<Path>..\Microsoft Flight Simulator X SDK\SDK\Environment Kit\Traffic Toolbox SDK\traffictoolbox.dll</Path>

</Launch.Addon>


-<Launch.Addon>

<Name>Visual Effects Tool</Name>

<Disabled>True</Disabled>

<ManualLoad>False</ManualLoad>

<Path>..\Microsoft Flight Simulator X SDK\SDK\Environment Kit\Special Effects SDK\visualfxtool.dll</Path>

</Launch.Addon>


-<Launch.Addon>

<Name>Captain Sim Menu</Name>

<Disabled>False</Disabled>

<Path>Captain_Sim\Captain_Sim.b757.menu.dll</Path>

</Launch.Addon>


-<Launch.Addon>

<Name>Captain Sim 757 Sound</Name>

<Disabled>False</Disabled>

<Path>Captain_Sim\757\cs.sound.dll</Path>

</Launch.Addon>


-<Launch.Addon>

<Name>FSUIPC 4</Name>

<Disabled>False</Disabled>

<Path>Modules\FSUIPC4.dll</Path>

</Launch.Addon>

</SimBase.Document>

I copied it.  Brought up the RUN prompt again and pasted this:
%AppData%\Microsoft\FSX-SE\dll.xml

I then get the message:

Location not available....location doesn't exist. 

Not sure if this matters but I have never had FSX on this laptop until I saw it was available on Steam.