This tutorial is for those of you who are having trouble when you click something on droseum20's all client mod menu tool you get a "un-handled expectation error, expected 4 but got 2" or something along those lines.
This tutorial should help you get rid of that annoying little error.

Make sure you Jtag/RGH is on 15574 Dev nand or you are using a Dev Kit, If you are not on Dev nand you can find a download in the download link spoil .. Down below.

If you are already on 15574 dev nand, You do not need to follow this tutorial, If you are not, Carry on reading.
1. Download and Extract the RGBuild v305, Extract the .rar file, You should have 2 folders and text document.
One folder should be called "_RGBuild_Beta0v305" and another called "15574-filesystem_0v305" .. Now read carefully..

Go in the folder named "15574-filesystem_0v305", Go in filesystems (not hdd-filesystems .. filesystems" you will see a folder named 15574-dev, Copy that folder, Back out and go to the folder named "_RGBuild_Beta0v305" and paste the "15574-dev" folder into the "filesystems" folder, Now go back to "15574-filesystem_0v305" open the "Loaders" folder and copy all the folders, Go back to "_RGBuild_Beta0v305" and paste those files in the "Loaders" folder, Now go to "RGBuild Launcher" and run it, Find where your nand is located aswell as your CPU Key.
Select hack type and make sure "version 15574" is checked, Click RGBuilder, A Window will open, Do its job and ask you to hit any key to close, Do so.
Now back in the "_RGBuild_Beta0v305" folder you will have a new file named "Image.15574-dev.bin, Rename that to "updlfash.bin"

Now, Have these files ready to copy to your USB:
"hdd-filesystems" < They can be located in "15574_filesystem_0v305" re-name "hdd-filesystems" to "filesystems" Have that folder ready.
In the "15574-filesystem_0v305" folder there will be a few files, find "bootanim.wmv" (this is a video file .. its needed!) and rgloader.ini, Have them ready to put on a USB.

Now plug your USB Into your laptop and Copy to it:
"filesystems"
"updflash"
"bootanim.wmv"
"rgloader.ini"

Now plug your USB Into your Jtag/RGH, Go to XeX Menu, Copy the "Filesystems" to the root of your HDD, aswell as "bootanim.wmv" and "rgloader.ini", Now power off your Jtag/RGH, Make sure you have your "updflash.bin" on your USB Device and its plugged into your Jtag/RGH, Boot the console into Xell by turning it on with the eject button, Wait untill it finds the "updflash.bin" and wait for it to finish writing, Once done, Un-plug your consoles power supply for 10 - 15 seconds, Turn it back on and you should have a custom boot logo and a Dev Dash! .. Step 1 finished!

You are now going to need to locate your IP Address, Which can be found in the same place as the following photo:
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*Please note*
To obtain a IP Address you will need some sort of internet going to your console, E.g, Wireless or Ethernet cable, You choose.

Once you have your IP, Memorise it, Or write it down, Go to Xbox Neighborhood .. Download link below .. Click "Add Xbox 360" Keep clicking untill it asks you to enter your IP, Once confirmed make the xbox you are adding now your "Default Xbox Development kit".
Now if your lazy like me, Go to the hard drive on your console via Neighborhood, Find all the .dll's in your MW2 folder, and Delete them, Yes delete them .. Or back them up and delete them.

Go to "Droseum20's all client menu", Open it up/Extract the .rar file, and go to the "xdrpc.rar" file, Extract it, and put this new xdrpc.dll in the "Droseum20's all client menu" folder, Launch "MW2 Online Menu" Click "Connect to Console" it should pop up saying connected (providing your still connected via Xbox neighborhood)

Now start the systemlink game, or if your lucky, online game, Wait till spawned, Click "Dump Clients" then go to the second "Players" tab, Which is the 3rd tab along, and click "Get Clients", Tick your name and Click "Start Lobby" you should get a verify screen on your console, Verify yourself, then go to the "Menu" tab, and click "Send Menu", Make sure its sent to "Client 0", The program may crash if it does, Leave it, and Open it up again.

Enjoy and Please Like the video for my hours of hard work! Peace guys.

All in the video description