Most (all?) OAuth resources - both information about the protocol and code libraries for easily using them in your own applications - one seems to find on the internet seem to a
DotNetOpenAuth currently only works on the full desktop .NET Framework 3.5 and later.
There are mild designs to support .NET Compact Framework in the future for OAuth consumers as you need, but it needs an actual feature request filed, and funding. If you can do one or both of these it will increase the speed that this feature can be delivered.
That said, someone has already published a sample OAuth 1.0a implementation for .NET Compact Framework that may be useful to you.
Similar question: Looking for OAuth 1.0a sample code for .NET compact framework