SFF files are produced from 454 sequencing runs! See here for more information http://www.mathworks.com/matlabcentral/fx_files/22864/1/content/sffdemo.html
You can download SFF files from the NCBI Sequence Read Archive http://trace.ncbi.nlm.nih.gov/Traces/sra/
You may want to find a metagenomic study of interest, for example an analysis of bacterial communities in the Baltic Sea. From there, you can find the associated 454 sequence data. I don't completely understand what you are trying to do, but I hope that helps.