I don't have Maya, but if you take that character as a basis, you should be able to modify it in Maya as instructed in the whitepaper, export as FBX, and then use 3dXchange to convert it back to an iClone standard character.

It doesn't use the Maya Exporter. It uses an FBX version of the STANDARD character suitable to be imported into Maya (available in the 3DX Pro resource pack), where it can be modified, and then exported from Maya again as FBX. 3DXchange only comes into play at this point, in order to convert the modified FBX file into an iClone character file. It's all in the whitepaper. I wished I had Maja so that I could prove to you that the procedure works. Maybe somebody could try?

I imported the FBX file from the resource pack via 3DXchange into iClone and it stays a standard character. It only works for this particular FBX file, which you can modify in Maya. If you happen to have Maya, why not try it? Just take the file, import into Maya, export again as FBX, load into 3DXchange and export to iClone. In 3DXchange it should say Standard Character.

Apparently, the FBX file from the resource pack contains certain information that signifies it as a standard character and 3DXchange just converts that information. In contract, FBX files you get by exporting characters from, from example, DAZ don't have that information, so they will not be considered standard characters.

The way to look at this is that FBX is only an exchange format (XML actually), which allows any kind of data to be exchanged between applications, in theory at least. But, as each application has their own bone system and mesh configuration for characters, the receiving application may not know what to do with all the information that it receives.