Have you tried making the setup as so;
Set the installer to create shortcut parameters which point to the default game folder with these switches-
"C:\Program Files\Novalogic\Delta Force Xtreme 2\dfx2.exe" /
mydfusamod dfusa
This points to the newly installed folder
mydfusamod and reads the pff file
dfusa.
Use any free compiler for the installer and use ravens pff tools to create and pack the pff.
you may need 2 (pff files) if you enable editing of the mods ie
med.pff.
you can change menu screens and and game sounds if you wish.
This is a less risky install for users (also your exe for your mod is too big and causes lagging on external drives)
Doing it this way it uses the DFX(2) exe to run which is (legal)