In the \"old\" FB iOS SDK I could receive user information via the following:
NSMutableDictionary *params = [NSMutableDictionary dictionaryWithObjectsAndKeys
Did you read the source code of the 3.0 SDK? There is a method that I think is identical:
- (FBRequest*)requestWithMethodName:(NSString *)methodName andParams:(NSMutableDictionary *)params andHttpMethod:(NSString *)httpMethod andDelegate:(id )delegate;