Don’t think that other thread addressed how to do this.
Honestly, the easiest solution would be to just hard code the links to checkout. You can copy the HTML generated by the default membership levels page if you like it… and just cut out the levels you want.
You can use the [checkout_button level=”3″] shortcode to generate a button/link to the checkout page for level 3.
What this won’t have is the functionality to show “Your Level” if the user has that level or to automatically add new levels when they are added. You’ll have to manually update them, but it is straightforward to do and easy to customize.
Alternatively, you can copy the code in the levels page here (https://github.com/strangerstudios/paid-memberships-pro/blob/dev/pages/levels.php) into a custom template or something.
Hope this helps.