Before starting configuration, make sure the license is active and B2B extension is enabled. (Default store configuration)

1. Setting up the separate store that will contain B2B

Go to System->Manage Stores submenu
Create the separate website with the store and some default store view.
Make sure to put the proper code to store view (this will be used in next steps)

2. Configuring Base URL in newly created store

Setup the link to match the code from newly created store view in the previous step

Go to CMS->Pages submenu
Find 'home' URL key in the table

Setup CMS homepage to match newly created store view

3. Creating the subfolder (could be used as the subdomain as well)

Go to Magento root and create the directory with the name that matches newly created store view code
Create symbolic links to match Magento root js/skin/media folders within
created folder

Create index.php inside the newly created folder with some updates matched on the screenshot below (the last row should contain proper code from previous steps - in our case, it's 'b2b')

.htaccess could match Magento root one

4. Setting up specific B2B configurations

Setup Wholesale store setting to match our used store view

Allow navigating to the B2B homepage (login) page for needed customer groups

Restrict access to B2B homepage for customer groups (it's IMPORTANT as you won't be able to see login page without this step)

5. What do pages we receive? How can we log in? Where to create new wholesale?

After steps above, we should receive 2 pages to work with
In our case they are:

{homepage}/{folder_name}/index.php/portal/account/register/ or
{homepage}/{folder_name}/portal/account/register/ for Registration

{homepage}/{folder_name}/ for Login

OR if you have subdomain configured to {folder_name}:

{folder_name}.{homepage}/index.php/portal/account/register/ or
{folder_name}.{homepage}/portal/account/register/ for Registration

{folder_name}.{homepage}/ for Login

So now you could proceed with configuring the pages with text/background/logos etc.