Since the ClientCallback functionality was not introduced until version 3.2 you will not be able to get callbacks to function without further modifications to the core.  I belive you will need to replace out the default.aspx.vb file and recompile... however, at this point one would ask why you wouldn't simply upgrade to 3.2.2?

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Ready already I work, the steps are: 

1.  To copy asembly "DotNetNuke.WebUtility.dll" of version 3.2.2 of DNN.

 2.  To copy folder/js of version 3.2.2 of DNN.

3.  To Edit the file default.aspx.vb of version 3.0.13 of DNN and to add the line:

DotNetNuke.UI.Utilities.ClientAPI.HandleClientAPICallbackEvent(Me)

at the end of page_init  and recompile the project of dotnetnuke to generate new asembly dotnetnuke.dll