Eduard, actually you were clear, I was just skimming the posts and missed what you were asking. I just reread yours before reading the other replies and I caught it.
this subject comes up on different forums about every 6 months. I need to take the time to detail my method. Of course there are a lot of ways to do this. I prefer the sled because it worked for me.
Essentially what you need it something that will hold the part steady at 7 degrees to the fence and then tilt the blade to 45 degree. As was stated it's not exactly 45 but I think it will be close enough on that taper.
I just took a larger piece of luan ply I had laying around and straighted one edge that would go against the fence. Then I carefully marked my 7 degree (or whatever mine was) on there. I found it simpler for me to work with a slope. So I converted my angle to 1/2" rise per foot of length (or what ever that works out too) and use a carpenters framing square. That was easier for me.
Then once I got my lines marked, I just added a few scrap blocks to push the blank up against. These were just scraps! Nothing fancy. Think drywall screws and scraps off the floor. Be sure and put blocks on a side and bottom so that you put each part in the same place!! Now that gives you the first sled.
The second one is the same principle but it's different. Now you going to be locating/registering off the previous cut 7 degree angle. So now you have to double the slope or set the part at a 14 degree angle from the cut side. It is still 7 degrees from the center line. (confused yet?) You also need to keep in mind where the 45 is. If I remember right I had to run the second part upside down compared to the first cut.
The simplest thing is if you have a bandsaw or with a handsaw even is to cut out a part to look at. Just a small piece and it doesn't have to accurate or even close. It just gives you something to hold in your hand and visualize what you need to do. How it should look sitting on the table saw sled. It will help you visualize the way the jig needs to be.
This is not a complex jig at all. It just takes some thinking to have it in your minds eye first. When I built mine I took a sharpie and marked "1st cut-face down. "2nd cut face up and upside down" etc so that I didn't mess up when I cut the final pieces. I marked several items on mine so I didn't have to rethink it.
I have made two sets of tapered columns and this is the last set I made for inside the house. Thinking through the cuts took longer than actually building them did.