Patching GTAIV to work on GTA Connected

The following instructions apply to a default GTAIV: Complete Edition directory.

It includes every Episode in one directory so you will be able to switch between Episodes and join any Server without issues

Install Instructions

Download the patch for either 1.0.8.0 or 1.0.7.0. (1.0.8.0 is recommended)
Unzip it, it should make a folder called Retail.
Drag the Retail folder into your GTAIV Directory. Don't move the files out of the folder! Just move the whole folder itself.
Open the GTA Connected launcher and select Tools > Game Settings. Choose Grand Theft Auto IV from the Game dropdown list.
Next to "Game EXE Path", click the Browse button to set the path for the exe to GTAIV.exe inside the new Retail folder in your GTAIV directory:

 Default Steam Path: C:\Program Files (x86)\Steam\steamapps\common\Grand Theft Auto IV\GTAIV\Retail\GTAIV.exe

Press UP key to bring up phone
Go down and press Multiplayer > Games
Press Custom Match to see any active lobbies. Join by double-clicking Lobby (if double-click doesn't work, press DOWN and ENTER)
If you know what Lobby is currently being played (e.g. through holding TAB if the server includes v-scoreboard), you can directly connect to a Lobby through QuickMatch on the phone
Press Y to chat in-game

If you've followed these instructions correctly, the original files should be intact and unmodified. This means Steam/Rockstar Launcher won't force the files to be reverted, and you can play GTAIV: Complete Edition on GTA Connected and also play the normal GTAIV: Complete Edition through Steam/Rockstar Launcher