How do i get those mods on computer?
Extract the files provided by Eagle to any place you want
Download IMGTool (I dont think i can give link here :S)
Open IMGtool, open file gta3.img with IMGtool (Located in 'Models' Folder in your GTAVC directory)
press F2 (Search)
Put in "police" as the field
remove the "police.txd" and "police.dff" files using IMGtool
Add the new "police.txd" and "police.dff" files from the folder where you extracted them.
Enjoy!