Diana,
 
Here is my experience with earmites, hope it is of some use.
 
When my Thor got earmites (only picked up via a routine examination), my
vet first prescribed a liquid 'insecticide'.  this was hard to administer
and not that effective.  After confirming it's suitability, my vet then
started a course of Ivomec Injectable (trade name Ivomectine).  This worked
well and was much easier to administer.  I later found out that this is now
the accepted method of treatment for mites in ferrets, though the Ivomec is
designed for cattle and pigs and has not been tested on ferrets.
 
My vet also told me that the wax (the earmites were causing it to be
produced in large amounts) would eventually come up to the outer ear, where
it can be wiped away.  He said that using 'Q-Tips' to clean the ear, can
compact the wax more than get it out.  During this time, he put some drops
of something (sorry can't remember what) to help break up the wax and I
just wiped it away as it came up to the outer ear.
 
Regards,
David and the down under ferrets, Thor & Grover
[Posted in FML issue 2569]