I've tried just about every PC remote, and would love to help. But it isn't possible to add any commands using that model. That's my point. You need an MCE dongle if you want any such flexibility. The Chinavision has only basic commands, that's it.
Besides the 4 you already mentioned, Chinavision is also missing Record, Green Button and won't properly wake. So compared to other options like Ortek and MCE, it is indeed the worst possible option.
If you insist on keeping it, you can do A-Z with triple tap. So, 16 macros (sequences) would do the trick. But I think Harmony is limited to 10 sequences per activity. There may be a way to do something more with Event Ghost, but I don't think it works with Chinavision's odd protocol. I could be mistaken. This is a case of finding the right tool for the job. The Chinavision is not the right tool.