Shared classpath is manipulated by adding the listed jars to the generated catalina.properties, in the common.loader property. Currently cargo adds the file paths in directly, but this does not work with windows path names with drive letters, backslashes etc. The correct behaviour (as hinted in the comment next to the shared.loader property below) is to encode the file paths as file: URLs.
Attached is a patch against cargo-core-1.0 to add the paths to the file as URLs. I haven't tested this on a unixy system, but see no reason why it shouldn't work on those as well as windows.