Our dear Shepherd, Bishop Edward Kmiec has addressed the issue as any orthodox Catholic Church leader would - with clarity, truth and succinctly to the point. From the February edition of Western New York Catholic, emphasis mine:
The Buffalo News recently (Jan. 4, 2009) reported on a group called Spiritus Christi that holds a Eucharistic worship each week as a sort of alternate Catholic Church. A few members of the group, including the presiding priest, remarked that they are Catholics who disagree with some of the requirements for participation in the Eucharist in the Roman Catholic Church. From the tenor of the article in the News, it seems that the Catholic Church is not progressive enough for these worshipers.
However, one cannot belong to a group such as Spiritus Christi or the traditionalist church of Marcel Lefebvre and at the same time be a faithful Roman Catholic. To be a faithful Catholic, a baptized person commits herself or himself to worship and live the Christian life under the direction of the bishop of the local church (the diocese).
Through the bishop, the local church is in communion with the worldwide college of bishops, who teach the Gospel, celebrate the sacraments, and organize the Church with and under the bishop of Rome, the pope. In this way the Church is one, holy, catholic and apostolic.
There is no other way to be a Roman Catholic.
Thank you, Bishop Kmiec. We are blessed to have you in the Diocese of Buffalo.