In looking at the mysql doc it loooks like this isn't possible:
13.5.4.15. SHOW PROCESSLIST Syntax
SHOW [FULL] PROCESSLIST
http://dev.mysql.com/doc/mysql/en/show-processlist.html
But, a couple of ways that I achieve this is by using the command below
if you have grep and cut availble:
mysqladmin processlist | grep <host> | cut -d '|' -f1-8
Or by installing mytop which allows you to filter on host using regexp
http://jeremy.zawodny.com/mysql/mytop/