How to install scope.png files to w_rifle.wtd, w_psg.wtd or w_e2_dsr1.wtd files using SparkIV.

Open SparkIV, 

C:\Program Files\Rockstar Games\EFLC\pc\models\cdimages\weapons.iso

or

C:\Program Files\Rockstar Games\GTA4\pc\models\cdimages\weapons.iso

or

C:\Program Files\Rockstar Games\EFLC\TBoGT\pc\models\cdimages\weapons_e2.iso

Click w_rifle.wtd, w_psg.wtd or w_e2_dsr1.wtd, click Edit

While editing the .wtd file, click target and import the .png file to target.

 