Find a 48 oz measure and use that amount of water for a full pot.
You need something besides the carafe as the machine will start brewing as soon as you start to add the water. You won't be able to use the glass carafe as you won't have time to pour the water and get it under the filter before it starts dropping coffee.
You might be able to find one in a thrift shop or call the person you got the brewer from and ask if they have the Bunn beaker and just forgot to give it to you.
The Bunn one is narrow (on the right in this pic) so you know what it looks like
Got it, thanks for the size. The seller didn't even know what I was talking about so it's obviously long gone. I'll just have to fill the Pyrex 3 times for a full pot. The parts that I could see were all extremely clean; looks barely used. I'm extremely excited to get it going, thanks for all the guidance so far, Mick!