I tried the Fractionated Morse Cipher on the Morse Code text from the entrance of the Kryptos installation.

Fractionated Morse Code Cipher

I gave it enough effort that I don’t see this as being the means for us to retrieve the keywords.  For someone starting with Kryptos, they would be starting at the easiest point with the Morse code and therefore shouldn’t need to extravagant things as they wouldn’t expect that they were needed to do so.  All the same, I tried a variety of alphabets and keyed-alphabets with no luck. 

When Sanborn talks about a series of doorways, is it possible he means that literally?