There are no specific universal commands, each company has their own process and procedure. You have to take direction from them. With my local data center, I entered the request into their ticketing system, including the email’d LOA. they then began the negotiation with all of their upstream providers. Some of them would not accept the email’d LOA, so I needed to get the letterhead version from (at the time) Brian. It took about three weeks of back and forth to get it set up and running. They did a static route of my allocation to my router in the DC, and I took it from there.
Later I split my allocation in half and sent part of it to Vultr (this required new licenses from ARDC). Vultr has a web form you fill out and submit. They do an email verification with ARDC, and I was working within about three hours from my initial submission (which is really quite amazing). At Vultr you must run a routing daemon on your host and speak BGP to their network. I chose to use BIRD (Bird Internet Routing Daemon) on my Debian host. The details on how to set that part up is well documented on their web site. The Vultr procedure is unique to Vultr, so posting it here would serve no purpose.
Many Data Center’s do not offer the service. Perhaps that has something to do with your lack of answers.