You can create custom php.ini in your account and add this capability.
To configure a site wide php.ini, create it in the root directory(/home/user/) and add the following line to .htaccess:
suPHP_ConfigPath /home/user
Once you have placed the php.ini as above,you can now configure browscap setting in php.ini and you can point it to the browscap.ini file on your account.
Note : be sure to change "user" with correct cPanel user name.