No, variable substitution is not available.
You can define targets to crawl down a path by limiting the depth; however, you cannot use wildcards. For example, each of the following target definitions will find the badfile.txt if it is in the path:
//server/share/depth1/depth2/depth3 (This scans only those files in depth3 and below, for example, if there is a depth 4)
//server/share/depth1,,2 (This scan continues down 2 depths, below depth 1 to depth 3, and does not scan anything below depth3)
//server/share (This scans the entire directory structure, all depths)
For example: /home/cam/bad_file1.txt would be placed in Quarentine/cam/bad_file1.txt