When I try to install SilverStripe 2.3.1 everything is find execpt for :

Is the .htaccess file writeable? User 'apache' needs to be able to write to this file:
/home/wormat/domains/swc-hosting.co.cc/public_html/cms/.htaccess

The file is currently owned by 'root'. There is no user-group that contains both the web-server user and the owner of this file. Change the ownership of the file, create a new group, or temporarily make the file writeable by everyone during the install process.

The problem is, there's no .htaccess file and the guides mentioned in the INSTALL.txt file don't seem to exist.

also this
Warning: fileowner() [function.fileowner]: stat failed for /home/wormat/domains/swc-hosting.co.cc/public_html/cms/.htaccess in /home/wormat/domains/swc-hosting.co.cc/public_html/cms/install.php on line 414

is shown at the top.

I have the same problem

User '_www' needs to be able to write to this file:
/Users/Vitaliy/Sites/test.net.ua/.htaccess

The file is currently owned by 'root'. There is no user-group that contains both the web-server user and the owner of this file. Change the ownership of the file, create a new group, or temporarily make the file writeable by everyone during the install process.
Tell me how you decided to

I use a Mac

Just create a file called .htaccess then it should work. Make sure it has writable permissions :)

Also note on a mac / windows sometimes the .htaccess file will be hidden from view. On a mac machine you can check if this exists by using Terminal.