I think the answer will be running Vuze http://azureus.sourceforge.net/
using Icedtea and the ARM SWT https://garage.maemo.org/projects/swt-hildon/
not 100% clear how to pass the magnet link to Vuze from Microb but it should be a few hours of effort at most for a competent java user who can pack it into a deb and stick it on the repos for long term Maemo fame. The only question is how the UI will look.