Yes, you can disable it for a domain from .htaccess. Just add the following code in .htaccess of the domain:
<IfModule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</IfModule>
This will work only if you have old version of mod_security installed on the server. You cannot disable mod_security2 using .htaccess. For more details to bypass mod_security2, kindly refer
http://blog.webhostingdiscussion.net/site-and-server-security/wordpress-and-mod_security2-issues.htmHowever, for security majors it is not recommended to disable it.
Kailash