I am not familiar with ucLinux OS and not sure what are the MCU and memory requirements to implement it. However if this OS can be implemented on a standard 8032 MCU and a standard Flash memory, then you should be able to implement it with an uPDS.
If no answers, it means surely that no OS is supported by the upsd3200. It would be interesting to have this opportunity to manage memory, multithreads, process.