Syslinux from USB Stick: boot the next hard disk in the boot sequence

I use the great Syslinux bootloader to boot the frugal installation of Slacko PuppyLinux from my Usb Stick, in this way i have a complete portable OS always with me that i can use for every evenience when i can use a pc that isn't mine, for example to surfing the web with my synced bookmarks in FireFox.

Syslinux is fully customizable and in my boot menu i added a voice to simply boot the next hard disk in the boot sequence totally bypassing the usb stick, in this way for example we can boot Windows from the hard drive without knowing the disk and the partition form which it have to boot.

To do this i used the chain.c32(*) in this way:

LABEL std
    MENU LABEL Standard Boot
    COM32 whichsys.c32
    APPEND -iso- localboot.c32 -1 -sys- chain.c32 hd1 swap