I just saw that this question is old "Mar 7 11" but for those who still face this problem;
Here is the guidance for them.
1) Read and implement the following starting guideline from the myspace documentation.
http://wiki.developer.myspace.com/index.php?title=Example_Application:_Hello_World
By following this guideline you will be able to setup the app setup at myspace like you do for facebook or twitter.
2) Once you will be done with it, you can verify the auth and other services from the api tool:
http://developer.myspace.com/community/myspace/testandtinker.aspx
3) Download the Ios sdk with a demo project from the following link:
http://code.google.com/p/myspace-iphone-sdk/
4) Once you will be able to run the demo/example ios demo.Try to see the file in "MySpaceSDKServices.plist" in the demo sdk project and edit it accordingly the files settings done at the myspace app creation panel.
Hope it will be beneficial for someone fighting with it :).