Off-site Native Vegetation

Can anyone clarify how we can achieve SSc5.1 through the use of off-site native vegetation? Do we use an alternative compliance approach and submit forms from LEED EBOM for this same credit? I am confused as to why the credit language discusses (almost as an afterthought) the use of an off-site land trust donation as an option but then does not include it in the forms. Has anyone earned this credit through this approach? The credit language for Case 2 of LEED CS SSc5.1: "Case 2. Previously developed areas or graded sites Restore or protect a minimum of 50% of the site (excluding the building footprint) or 20% of the total site area (including building footprint), whichever is greater, with native or adapted vegetation. Projects earning SS Credit 2: Development Density and Community Connectivity may include vegetated roof surface in this calculation if the plants are native or adapted, provide habitat, and promote biodiversity. Projects with limited landscape opportunities may also donate offsiteland in perpetuity, equal to 60% of the previously developed area (including the building footprint), to a land trust within the same EPA Level III Ecoregion identified for the project site. The land trust mustadhere to the Land Trust Alliance 'Land Trust Standards andPractices' 2004 Revision."