We present a simple implementation of a token-based distributed mutual exclusion algorithm for multithreaded systems. Several per-node requests could be issued by threads running at each node. Our algorithm relies on special-purpose alien threads running at host processors on behalf of threads running at other processors. The algorithm uses a tree to route requests for the token. We present a performance simulation study comparing two versions of our algorithm with a known algorithm based on path reversal on trees. Results show that our algorithm performs very well under a high load of requests while obtaining acceptable performance under a light load.