Countries are diversifying their payments, and this is a global trend. This article examines (as an institutional innovation project) a unique mechanism that enables participants in foreign economic activity to make payments in their national currencies – Sistema de Pagos en Monedas Locales (SML) – in South American countries. Unlike technological innovations (blockchain, smart contracts), the SML institutional innovation focuses on restructuring the rules of interaction between economic agents, reducing transaction costs, and creating an alternative institutional environment for foreign trade operations. The aim of the study is to identify success factors, assess the contribution to business competitiveness, and the limitations of scaling this institutional innovation project using the example of cross-border SML. This approach aims to formulate universal lessons and develop a methodology for creating similar systems. Based on an analysis of the system’s evolution (2008–2026), its operational mechanism, and statistical data, it was established that the SML reduces transaction costs for small and medium-sized enterprises (SMEs) by 15–20%, performs a countercyclical function during periods of currency crises, and serves as an alternative channel for imports in conditions of dollar liquidity shortages. However, the system’s scalability is constrained by a number of limitations: the lack of mechanisms for hedging currency risks and lending, the lack of operational continuity (the system does not function on holidays and weekends), the persistence of structural asymmetries (more than 99% of transactions are accounted for by Brazilian exports to Argentina), and the final dollar clearing between central banks. The following success factors have been systematized: voluntary participation, focus on SMEs as “early adopters”, a simple and understandable settlement cycle (D+0, D+1, D+2), and institutional support from central banks and governments. A roadmap for the creation and scaling of institutional innovation projects has been developed, comprising four stages (inception, development, maturity, and expansion) across four areas (financial mechanism, technological platform, institutions and law, clients and adoption). The results are applicable to the design of similar systems, for example, within the EAEU or BRICS.