Newbie: change data dir and user.

Hi. I need change data dir for percona. But, when i do init with this patameters:

sudo mysqld --initialize --user=[user] --basedir=/home/[user]/percona --datadir=/home/[user]/percona/base

i can`t connect to database: ERROR 1045 (28000): Access denied for user ‘root’@‘localhost’ (using password: YES).
But, when i do like that: sudo mysqld --initialize --user=mysql --basedir=/usr --datadir=/var/lib/mysql all work good

And one more question: how to change mysql user to [user]? It is necessary that the perсona work on behalf of the user [user]