As I saw people already planning "incorrect customs," I thought I'd serve as the Ubernerd and post the following:
I don't think (Out of Snow Gear) General Madine and General Rieekan wear the same uniforms. This custom idea may be unwarranted.
The Rebel Alliance was made up out of the local military from all the rebelling systems.
General Rieekan was Alderaanian. As a command officer, he'd wear a uniform similar to Captain Antilles.
Their soldiers traditionally wore the uniforms like the Rebel Fleet Troopers (Tantive IV Defenders).
General Madine was Corellian. An Imperial military commander that oversaw the Diktat of Corellia, after the Battle of Yavin, while Corellia tried to officially play a neutral role, a lot of its highest officials were conspirators in the Rebel Alliance, including Garm Bel Ibis, who with Mon Mothma (of Chandrilla) and Bail Organa (of Alderaan) formed the Alliance in the first place. But the worlds remained carefully benign after the Empire showed its resolve with the Death Star at Alderaan.
In any case, Madine wears the Corellian uniform. When command of the Endor mission falls to newly promoted General Han Solo, also a Corellian, Princess Leia wears a Corellian uniform to show her solidarity with other Alliance troops, and her respect (and love) for her Corellian commander (Han).
In any case, if you want to make an accurate figure of General Rieekan OUT OF SNOW GEAR, use Captian Antilles' body for your headswap.