What is the viability of Intelligent Design as a supplement to chemical abiogenesis and Darwinian Evolution?
I think the issue with Intelligent Design is not so much that its patently proven wrong.  On the contrary, the problem is that it not a scientific hypothesis and so it really isn't a scientific question.  

If I may, the basis of the scientific method, as formulated by Karl Popper, but commonly in use today, is that science is the putting forth of theories of cause and effect which are testable (or if we are being precise, falsifiable).  

That is to say, you put forth a theory such as 'God/some diety figure made all living things' and then you perform an experiment which can differentiate whether the hypothesis or its null version (i.e. 'no intelligence is the source of life / biology is the result of accidents') is more likely true.  

This question will not be testable in a way to answer enough of the reasonable skeptical questions ( or at least so far it has not).  Experiments have been tried, but they are often not acceptable to everyone.  For instance the idea that some biological structures such as the eye or the flagellar motor are too complex to have evolved through a typical Darwinian process which involves a series of small changes are almost biological theology - one can always hypothesize a more inhuman God (probably appropriate) who acts and 'thinks' in such an inhuman manner that anything you see could be created/inspired.  While I think you should feel free to believe either way, I also believe that this is not an argument that can be won or lost.  The tendency for any experiment to confirm both the hypothesis and its inverse seem inescapable.  

That is to say, that biology and physics will ultimately fail where philosophy and logic also did in proving the existence of God, besides the less interesting truism that if God does exist, the deity is consistently elusive to proof.  

On the other side of the coin, the proof that life has emerged from naturally occurring phenomena such as lighting strikes in a prebiotic environment are interesting since it shows that nucleotides and amino acids might have been available without metabolic pathways to synthesize them.  In its way, the molecular origins of life on earth is a question which is really testable only in theory.  

Anyone who thinks they are going to re-create the event of the beginning of life itself is scientifically on thin ice - the prebiotic environment may have extended to the entire surface and atmosphere of the earth as well as down into mud and bodies of water and sat incubating for maybe hundreds of millions of years.  The idea that the fundamental moment of life generation is just going to show up on a well chosen set of conditions in a 500 ml flasks with some electrodes attached is an idea that workers in the field don't even entertain.  

Until such an experiment produces life, the work will have to rely upon the idea that there was a moment in time where the necessary elements came together.  

This being said, cosmology, biogenesis work has approached the moment of the genesis of life asymptotically with amazing clarity.  

The RNAWorld hypothesis strongly supports the idea that an early biotic system might have been very simple - maybe only RNA and its four nucleotides.  Clearly after what Dawkins calls a replicator exists, then the pathway to living things as we know them is pretty easy to envision.  

I should add that I'm not one of those people who think that science is everything - the trend that is impoverishing some humanities program is alarming to me.  Its just that some things are not science.