First of all, if you'd rather use the .htaccess than the php.ini capabilities of a phpsuexec environment, then shame on you. But, we have some customers who are terrified of php.ini and would rather use the .htaccess. So what? Ok, well there is a workaround.
The connecting piece is the htscanner extension - she includes installation instructions and how to include it into your PHP installation (as well as how to set the PHP values in the .htaccess).