>> DBI connect('sefovan:localhost','koha',...) failed: Client does not support 
>> authentication protocolrequested by server; consider upgrading MySQL client at 
>> C:\usr\koha-2.2.0RC2\modules/C4/Context.pm line 409.

This problem arises from the mysql authentication change documented at:
http://dev.mysql.com/doc/mysql/en/old-client.html

You can overcome the problem by editing line 1808 of Install.pm from:

print system("$mysqldir/bin/mysql -u$mysqluser -e \"insert into user (Host,User,Password) values
('$hostname','$user',password('$pass'))\" mysql\;"); 

to:  

print system("$mysqldir/bin/mysql -u$mysqluser -e \"insert into user (Host,User,Password) values
('$hostname','$user',OLD_PASSWORD('$pass'))\" mysql\;");