there is no official C++ source code available for the original silkroad server.
most private servers use compiled server binaries and customize them through reverse engineering, binary patching, DLL hooks, database edits, configuration files, and packet manipulation.
tools like
Quote:
are commonly used to understand the server logic. quests, events, items, rates, etc. can then be implemented by modifying the database/configuration or hooking/patching the relevant server functions.
so basically private server development is usually reverse engineering + binary modification, not compiling the original C++ source.