Yes but… it’s going to take a little bit of rewiring. The power inserter will work on any cable in your DIRECTV system but it will only work on one port on your splitter.
Take a look at this typical 8-way splitter:
The port at the top left has a red center to it, which indicates that in addition to passing your satellite signal through it, it will also pass power. The other 7 ports will actually block power from being passed. The line from the power inserter must go into this upper left port (generally called port 1) on the splitter, but that doesn’t mean that you need to leave it where it is.
The challenge is finding out which cable goes where without destroying your whole system. You can slowly disconnect one cable at a time to try to trace the line from place to place or you can use a cable tester like this one. Once you know where each cable goes in your house, it’s easy to swap them around so you can put the power inserter where you want it to be.