Many people out there are using Windows Live Messenger as IM, and for some reason they need to open more than one instance (polygamy). But that does not work without a patch for Windows Live Messenger. In this post, I’ll explain how to patch your own Windows Live Messenger by yourself. Some may say there are patches already exist out there, my answer; I don’t trust it because it might contain Spyware 
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Tools:
- Debugger (OllyDbg) {for the dirty work} :p
- Hex Editor (xvi32) {if you know the address for the magic line}
The short way (for WLM 8.5):
- Copy & Rename Windows Live Messenger “msnmsgr.exe” to something else; let say “msnmsgr-multi.exe”
- Open msnmsgr-multi.exe by Hex Editor (maybe xvi32)
- Go to Address {8CF06}
- Replace {0F 84 BA 77 00 00}
- With {90 90 90 90 90 90}
- Save it!
- That’s it, enjoy your Window Live Messenger
The long way (if you don’t know the magic address!):
- Open OllyDbg
- then Open then “msnmsgr.exe”
- Open “intermodular calls”; By right-click on CPU Window –> Search For –> All intermodular calls
- Sort “intermodular calls” by “Destination”, then type “CreateEvent”
- Click the first “CreateEvent” to highlight it in CPU Window
- You will notice Eventname of CreateEvent is “MSNMSGR”, locate the GetLastError that come after our CreateEvent
- Our magic line is the 2nd line after GetLastError {JE xxxxxxxx}. x = hex number
- Double-Click that line then replace {JE xxxxxxxx} with {nop} and make sure “Fill With NOP’s” is Checked then click Assemble then Cancel
- Now we are done, the only thing left is to save the changes; right-click in CPU Window; Copy to executable –> All modification; then select “Copy All”
- Then from the window that poped up; right-click –> save to file –> rename it if you want ( I usually do, in case I need the original one) , let say “msnmsgr-multi.exe”
- Close OllyDbg and enjoy your Windows Live Messenger