The developer of the TinyUmbrella program is preparing a new program with which we will be able to customize the ipsw in a similar way to that offered by PwnageTool or sn0wbreeze. The developer did not provide any details about the possible functions, but he specified that these changes will be made through a custom API that he is currently working on. With PwnageTool and sn0wbreeze we can make a custom ipsw jailbreak and activate it, so I'm thinking that TinyPwn could do something similar or maybe we'll have other options available in it. It is not yet known when this new program will be available, but as soon as it appears I will let you know.
