mysql 4 using backports

[cyril <dev@foneport.com>]

Hi

I really need to install Mysql 4 on my debian box. I am a recent convert from 
RedHat. I am running Debain stable packages but need some of the new 
funcitonality in mysql 4 in to port some of my apps properly. I was going to 
install from source but came accross backports and though I should try it. 

I am not very familar with apt yet. Should I remove the existing mysql 
packages first or can do an upgrade?

I have added 

deb http://uk.www.backports.org/debian stable mysql-dfsg

to sources.list

If I now run 'apt-cache search mysql' I get

W: Couldn't stat source package list http://www.backports.org 
stable/mysql-dfsg Packages 
(/var/lib/apt/lists/uk.www.backports.org_debian_dists_stable_mysql-dfsg_binary-i386_Packages) 
- stat (2 No such file or directory)

Does that mean I have to add lines under /var/lib/apt too?

any help appreciated

Cyril