It doesn't work. You can get a copy of Windows XP Home Edition and Professional Combo which was released by Microsoft. It has both Home Edition and Professional which are the most commonly installed SKUs. The Combo edition of Windows XP among Starter Edition are the rarest Windows XP SKUs and it might be a bit hard to find an original copy of it.
If you analyse the BootSector.bin used in the Combo edition, you will find upon boot, it will give you the option to choose:
[A] Windows XP Home Edition - English
[B] Windows XP Professional - English
Choose an option and press [Enter]:
and by selecting A, it will boot you into WXPH and if you choose B, it will boot into WXPP.
The WXPH folder is capable of installing Windows XP from \ENGLISH\WINXP\HOME and the WXPP folder will install from \ENGLISH\WINXP\PRO.
I hope that gave you an idea how Windows XP Multi-SKU setup works and how it is impossible to convert a Single-SKU image to Multi-SKU with the ISO Downloader. Also, there is no ei.cfg.
If you want the Combo edition, I am happy to PM you a link.