BN,
That's a really good question. At first I thought that, since you said you couldn't find your my.cnf file, all I had to do was help you locate it. I thought the location might be in phpinfo, but I looked in mine and it isn't; it tells me where php.ini is, and gives me a hint about Apache's httpd.conf, but no mention about my.cnf or my.ini.
Then I read where you talked about not having access to your server. I presume you mean you are using a web hosting service. Then I thought maybe you could put the line in .htaccess. But the docs only talk about Apache directives and php settings, not MySQL, in .htaccess.
So at this point, it wouldn't do any good to find my.cnf, since you wouldn't have write access to it anyway. The only thing I can think of is to contact tech support at your web host. Ask them if they have MySQL running in strict mode, and if so, is there some way you can turn it off. If not, would they be so kind as to turn it off. If not, switch hosts!
RLE