1) Create an own 'signup page' theme at Configuration > Design > Signup page theme by clicking "Edit theme" on the currently active theme
1.1.) Disabling the mini-site (information page)
- in that own theme look up main_static_html_doc.stpl and in that template file find the <body> tag and right under that tag (so into a new line) put this:
<h1>Under construction</h1>
<{*
and then find the </body> tag and right above that tag (so into a new line above that tag) put this:
*}>
1.2.) Disabling the affiliate-login form
- in that own theme look up main_aff_html_doc.stpl and
in that template file find the <body> tag and right under that tag (so into a new line) put this:
<h1>Under construction</h1>
<{*
and then find the </body> tag and right above that tag (so into a new line above that tag) put this:
*}>
1.3.) Disabling the signup form
- in that own theme look up main_signup_html_doc.stpl and
in that template file find the <body> tag and right under that tag (so into a new line) put this:
<h1>Under construction</h1>
<{*
and then find the </body> tag and right above that tag (so into a new line above that tag) put this:
*}>
That's it.