I need a document that describes the S-file, how is it build. I want to know if it's possible to find an instruction in flash memory, boot memory or ram memory just looking the S-file.
If you know what part of it that is data and what part that is code, then yes, even though it isn't easy. All instructions are there in hex, you will have to translate the op-codes to assembler.
The decoder application can be used to disassemble the content of an srecord, you have to specify the processor with the -proc option. It wont know if some byte is a constant or instructions, so data will be disassembled as unreasonable code.