I modified unecm to accept input from stdin. For pakkiso, here's how the process usually goes for unpacking:
read .7z from disk -> 7za extracts -> write .ecm file to disk -> read .ecm file from disk -> unecm decodes -> write .bin file to disk
read .7z from disk -> 7za extracts -> unecm decodes -> write .bin to disk
This requires somewhere around half the amount of data transferred to and from the hard drive meaning your hard drive should last longer. It's also a tiny bit faster, maybe 3-5 seconds. The program also now outputs execution time, is backwards compatible with v1.0, and I've improved the debug messages.
Here's how to call it:
7za e -so input.7z | unecm - output.bin
Download link: http://www.mediafire.com/?i12nyjjdnwa