Kan and Geneticin are both aminoglycosides and act, if
memory serves, the same way.  However, kan is specific for *prokaryotic*
ribosomes and geneticin (neomycin) is specific for *eukaryotic* ribosomes.
You have you use what you need depending upon the host you are using as
they can not be intermixed.

For example, Stratagene makes a nice vector called pBK-CMV which has NeoR
as its resistance marker.  It is a nice vector in that for bacteria, one
uses kanamycin and gets no satilite colonies.  The advantage is then had in
that you can take the vector, plunk it into your cell of choice, and use
G418 as your eukaryotic selection marker.  

For your case, it is the same thing:  you use kan while it is in bacteria,
but for your application in yeast, sorry... you're stuck and do need G418
(geneticin).  BTW- G418 does have inter-lot variability and ideally should
be tested in a killing curve with each new lot purchased....