Addon installation:

1. Open your Grand Theft Auto 5 folder
2. Navigate to mods > update > x64 > dlcpacks
3. Place "brownstreak" into "dlcpacks"
4. Load up OpenIV and navigate to mods > update >update.rpf > common > data
6. Extract "dlclist.xml"
7. Paste this line into the list:                 <Item>dlcpacks:\brownstreak\</Item>
8. Place "dlclist.xml" back to where it was extracted from

Train configuration installation:

1. Use OpenIV to navigate to mods > common.rpf > data > levels > gta5
2. Place the file "trains.xml" from either one of the "train config" folders into the folder in step 1.
3. Place both files from the "train stations" folder in the folder from step 1.

(Optional) Railroad Engineer configuration installation:

Place J10RailroadEngineer.ini into the GTA V root folder and replace the original. 
This simply adds the loco to the config and thus makes it driveable. If you have your own custom config, 
simply add "streak1" into the list of locomotives as instructed in the file.