Ad usum praecipuum sacerdotum Legionis
I would especially reinforce Grisez's observation about Legionary priests being able, and perhaps even obligated, to appeal outside of the Legion structure for Roman intervention in this unprecedented crisis. For example, 1983 CIC 212.3 states: "According to the knowledge, competence, and prestige which they possess, they [i.e., the Christian faithful, which includes Legionary priests] have the right and even at times the duty to manifest to the sacred pastors [up to and including the pope] their opinion on matters which pertain to the good of the Church and to make their opinion known to the rest of the Christian faithful, without prejudice to the integrity of faith and morals, with reverence toward their pastors, and attentive to common advantage and the dignity of persons." The canon takes on added weight when its placement, near the top of a list of the fundamental rights and duties of all the Christian faithful, is noticed.
2. Canons 691, 692, and especially 693, form the basic parameters of the exclaustration / excardination process for religious clerics interested in joining diocesan presbyterates or other institutes of religious life. Canon 270, though taken from norms on the excardination / incardination of secular priests, is also relevant. The text of the law, of course, is bare bones; a canonical commentary on the canons (there are many) will help orient the reader to the process.
Updated, 8 February 2009. George Weigel, senior fellow at the Ethics and Public Policy Center, has just published a compelling call for immediate intervention in the Legion by a personal delegate of the pope.