The Swedish Classical Radio will broadcast Sigurd von Koch's Piano Quintet from 1916 on December 14th in their programm "Klassisk förmiddag" (10.00 - 12.00 am) : http://sverigesradio.se/sida/tabla.aspx?programid=2562&date=2011-12-14
Sigurd was the father of Erland von Koch and, unlike his son, died at young age. His Violin Sonata in E Minor (1913) seems to be his only work that has been recorded.
Worldcat apparently lists recordings of at least one Sigurd Koch brief vocal work on CD and of the piano quintet, I think. The quintet on a CD from 2000 called "Swedish Quintets" with works by Kallstenius, von Koch and Fernström. See also
http://www.mic.stim.se/412566CD0052EF54/WebV5BiografierAZ/8783EA130EF1B43941256492002D2C87 (http://www.mic.stim.se/412566CD0052EF54/WebV5BiografierAZ/8783EA130EF1B43941256492002D2C87) - brief (8 recording, some duplication?) discography at bottom, not sure if they're all commercial or no.