The LT3080 is a current source based generator, that is, the reference voltage is set by the fixed 10uA flowing through the adjust pin and its external resistor. If so, I don't see (according to their schematic) why they say the input voltage is limited to 36V. Suppose for example I want to regulate a supply with 5V - 10V ripple at about 700V, and that I connect a 70MOhm resistor (approx.) to the adjust pin; how could the IC know that the input voltage is 700V since its reference is near the top voltage ?
The part actually supports 40V, it says 0 to 36V because that is the voltage range that the specifications of the part will work. The part has been tested for 0 to 36V.
The absolute maximum ratings are ratings for which the part will fail you can't go more than 40V relative to Vout
So you could do what you suggest if the voltage drop across a resistor was always more than 660V, thus keeping the voltage drop across the LT3080 under 40V.
Looks like it could work depending on the load: