I don't think you can use the TV remote to control Astro, unless you get some kind of "all-in-1" universal remote control, eg like this type:
http://www.chunghop.com/en/products_view.asp?id=137
That way you may keep all remote controls and just use 1 to control all
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Above old tread on Chunghop universal remote control. The link is dead. Have any one able to find the keycodes for the Chunghop RM-88 to control Beyond?