Cycles: How do I add an input socket to a node in cycles? I would like to add an input socket to the offset field on the image sequence node in cycles. Can this be done without using open shading language?
No, those node inputs represent hooks within the code that gets executed by Cycles itself. Not even OSL is enough in this case, you'd need to modify the source code of Cycles itself to allow frame number to accept arbitrary shader input instead of a fixed value.