A typical BOOTLIN setup: everything happens like when booting MS-DOS, but in CONFIG.SYS or AUTOEXEC.BAT, BOOTLIN is invoked. Typically, a program like BOOT.SYS is used to choose among configuration sections in CONFIG.SYS and AUTOEXEC.BAT. This approach has the pleasant property that no boot sectors have to be altered.
Please refer to the documentation accompanying the package for installation instructions and further details.