One paper with CO-solubility in acetonitrile is the following:

Journal of Chemical and Engineering Data

Volume 30, Issue 3, July 1985, Pages 269-273

SOLUBILITY OF HYDROGEN IN 10 ORGANIC SOLVENTS AT 298. 15, 323. 15, AND 373. 15 K. (Article)

Brunner, Erwin

It is also interesting to check if there is any data available by using the DDBST overview or Thermolit by NIST:

http://ddbonline.ddbst.com/DDBSearch/onlineddboverview.exe

http://trc.nist.gov/thermolit/main/home.html#home

Best regards,

Petri

Dear Michael,

There is now a reference were to find the solubility, which was the primary goal of the person asking for information.

Regarding the  DDBST: It may also have data-sets that are not in the open literature and also some new data may have been published after Brunners article.

BR.

Petri