Which command lines did you running exactly?
Did you have any error running those lines?
Here is an example of the srec2flash utility.
The command syntax for the srec2flash utility is:
The utility outputs the file .flash, which you can download into the Nios development board using the command:
Generating S-Records for Use with the srec2flash utility.
Can you try this? Let me know if it works!
Here is the original file where I found this info - http://extras.springer.com/2004/978-3-662-06730-7/literature/wp/wp_srec_to_flash.pdf