creating custom proxy

Hi,
I am newbie in Spring.net side.I have gone through its Documentation on AOP.
I realize that spring only support Advice on object which has base class type with abstract method.But I want to Use this feature on existing project and apply advices on existing code. Unfortunately existing code is not up to that level which is required by spring.net.
How can I create proxy or simply activate proxy object to apply Aspect on my required object's operation.
Any help would be appreciated.

Thanks,