Alternative to Rx (Reactive Extensions) for .net 3.5

I'm working on a .net 3.5 app and I'd like to know if there is a workaround or other software that can provide similar functionality to IObservable and es开发者_高级运维pecially Observable.FromEvent

The app runs inside mediabrowser so I absolutely have to stay with .net 3.5 otherwise I'd happily upgrade to 4.0.

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You dont need 4.0 if you want RX. You can have RX for 3.5