Have you tried with:
excel.Selection.Hyperlinks:Add({Anchor = excel.Selection, Address="http://www.bbc.co.uk/", TextToDisplay="BBC"} )
Anyway, if that fails (which probably will), you can take a look at the definition of the Add method (ActiveSheed.Hyperlinks.Add) using OleView, as suggested earlier.
That's because you are using named parameters, and I don't recall how LuaCom deals with those.
Named parameters are like a "shortcut" were you don't need to provide all arguments to a function if some of them are optional.
For instance, this function (not related to Excel)
HRESULT StartRecording(
[in] BSTR Path,
[in, optional, defaultvalue(0)] short Width,
[in, optional, defaultvalue(0)] short Height,
[in, optional, defaultvalue(0)] short FrameRate);
Could be invoked as StartRecording( Path="something", FrameRate=30 )
But, with LuaCom, you might need to invoke it passing nils for the arguments not provided.
StartRecording( "something", nil, nil, FrameRate=30 )
Hope that helps.