I think what he is asking its a really hard task, I think you need to do at least these steps:

1) Repartition the USB Flash Drive: you need a MBR format partition style and an active partition with a standard bootsector; most drives dont have this format by default.

2) Create and format a partition as HFS+

3) Dump the contents of the installer: its its ISO it should be not that difficult but its DMG it can be.

4) Make the USB Drive bootable with Chameleon: for this you need the manual installation as the install package only works in Mac.

For 1) I think you cant do that with windows, at least with Disk Manager, maybe with command line. I think third party partition tools like Parted Magic will let you do that.

For 2) Parted Magic lets you create HFS+ partitions but they are not recognized by OS X Installer. You can also format discs with HFS+ format with MacDrive but I've never tried that. At worst if you can boot any DVD installer you should be able to format the partition from there using Leopard's Disk Utility.

For 3) depends if its ISO or DMG. For ISO any program that understands HFS will let you extract the contents of the ISO to the USB Drive, but I'm not sure if they will lose some of the Mac-specific attributes. For DMG I think IsoBuster supports that too, also MacDrive can mount DMG files in Windows. I'm not sure if simple extraction will work but it probably should.

For 4) you have to use some third party tools to a) copy the boot0 file to the Flash Drive's MBR; and b) copy the boot1h file to the Flash drive's partition boot sector. For a) I dont know of any tool that can do that, maybe some generic MBR Backup/Restore program will do; for b) there are versions of dd command line for windows (dd.exe) but I've never used them; Third step for chameleon installer is just copying the boot file to the partition's root but that should be just plain copy even by drag and drop...

Hope this helps, keep in mind that I've never tried this so I could be wrong about some of the steps.