First shots with MPE-65mm macro lens

I've had this lens for several months, finally tried it yesterday and was promptly rained out. I can see that focus is going to be much more picky -- I was hand-holding and this little caterpillar about 1" long with the "don't touch me" irritating hairs was really moving:

http://gallery.photo.net/photo/6205420-lg.jpg

Crop of poisonous hairs:

http://gallery.photo.net/photo/6205421-lg.jpg

Another shot (focus is worse):

http://gallery.photo.net/photo/6205422-lg.jpg

And a hair crop:

http://gallery.photo.net/photo/6205423-lg.jpg

I get a double reflection from the Canon Macro Twin Lite MT-24EX, not sure if I need some type of diffuser that will fit in the very limited space available. Any suggestions?