If you don't have a chequip.s3d file then you're a bit stuck. This is the file that contains the character models that the new viewer can view and export, i.e. the pre-luclin model files. The global_xxx.s3d files contain the luclin models as far as I know and they won't work with the viewer.
chequip.s3d is a pain to find in the list of 3ds files, I've stared at the list for ages not being able to see it so I made the viewer auto-select it on startup
Maybe it's only installed with one of the expansions, I'm not sure to be honest, I've got them all installed on my machine.
There is a scale in the viewer by the way, it's on the middle mouse button I think, if not then it's on the right button
It has some problems when viewing really big models such as the dragon model, it's so big that by the time you've zoomed out enough to view the whole model most of it has dissappeared behind the back view plane. It doesn't affect the export though which is the only time you really need the 'scale on load' option turned off.
K.