yes, unfortunately you'll have to spray directly into the switch itself. The plastic cursor keys will act as an umbrella over the parts that need spraying otherwise.
If you get the lid off, the cursor keys should be easy to unclip & the the little tacts will be starring at you, begging for your attention.
I'm starting to think that Akai want us to go inside our MPCs, like its some kind of bonding process. Like in Star Trek The Movie when Voyager returns to be completed by the creator.
God I am one sad f**k!!!

This is the stuff to spray by all accounts:
http://store.caig.com/s.nl/sc.2/category.188/.fI think its D5 that everyone is using, hopefully someone will give a follow up post to verify this.
Think I'll have to get some myself if it'll save me loads of soldering.