Just short message that patch enables microsecond resolution in slow-log (see more https://www.percona.com/blog/2006/09/06/slow-query-log-analyzes-tools/) for 5.0.37 is available here:
www.percona.com/blog/files/patches/patch.slow-micro.5.0.37.diff
The patch for 5.0.41 :
www.percona.com/blog/files/patches/patch.slow-micro.5.0.41.diff
The 5.0.41 patch seems to be a copy of the 5.0.37 patch!? I see no difference and it sais
diff -ur mysql-5.0.37/include/my_time.h mysql-5.0.37-microslow/include/my_time.h