The part I found most relevant to Western Sahara was his effective building of coalitions between groups that were all interested in a just solution in the Congo. For example, he combined the efforts of Liverpool merchants, who wanted free trade on the Congo River, with missionary groups who wanted their converts protected.
I thought of a few groups with sometimes disparate aims that already have interests in Western Sahara and could be convinced to work together.
- The Algerian government
- Phosphate companies that've been shut out by Morocco
- Christian groups like Be Their Voice
- Other national liberation movements, like East Timor's ETAN
- Human rights groups like Amnesty and Human Rights Watch
- Left-wing Scandinavian political parties
- Groups dedicated to the Western Saharan cause like ARSO and AWSA
UPDATE: As Alle points out, support for Western Sahara doesn't have to be limited to leftist parties in Scandinavia, or anywhere for that matter. Western Sahara's appeal to all political persuasions bodes well for the future.