I recall going through quite some troubles and lots of Internet research while dealing with the interplay of the boot-loaders. The USB stick I used had Syslinux installed in the end. However, the first boot was performed from Grub(2) installed on my laptop. VMs were not on my radar at all so that method won't work.
Personally, I prefer Extlinux for its ease of use. If it works for you as I understand from your second previous post then that is fine.
The wiki article is not quite clear, indeed. Probably it would be better to install Extlinux on the USB-stick straight away. The easiest would be if one could use the same boot-loader as the one of a standard Linux installation. However, I do not see any way for achieving this with Grub2 without creating the bloated infrastructure in the file system. I will soon tend to the article.