How do I set up the PocketWizard Mini TT1 and Flex TT5 with a Buff monolight?

Disclaimer: I have never used PocketWizards, but I worked as a technical writer for a few decades. I just went through the maze of "documentation" on the PocketWizard website (looks a lot like a written-by-engineers wiki); so I see why you asked. :D

0. Since the 5DMkIV may be too new to be compatible with the TT1/TT5, you need to set at least the TT5 in Basic Trigger mode with the PocketWizard Utility which you can download and see instructions for here. The AlienBee B800/sync cable connection can't do TTL/HSS/remote power control anyway, so you're not losing any additional function this "single-pin mode" turns off. You also need to set (hopefully) camera compatibility and the two configurations the triggers let you use (e.g., you can use C.1 as your "single-pin" with the monolight, and C.2 as a TTL configuration for a speedlight). This only before the first use of the triggers.

1. Put the PocketWizard Mini TT1 on the camera hotshoe. [It can only be a transmitter].

2. Cable the PocketWizard Flex TT5 transceiver (can be either transmitter or receiver) to the 1/8" sync connector on the AlienBee B800 (a mono 3.5mm (1/8") to 3.5mm audio cable should work).

3. Power everything on “from the top down.” Start with the TT1, then the camera, then the monolight, then the receiver. Wait 2-3 seconds between each power on. Make sure you use the configuration setting (C.1/C.2) you set up in Step 0 on both units.

4. Set the PocketWizard units to use the same channel. Set a group on the TT5, and make sure that group is set to fire on the TT1.

5. Set the 5DMkIV so that it treats the Mini TT1 as if it were an on-camera speedlight; not a wireless master. Make sure all wireless flash settings in the camera are disabled, and that flash is turned on.

6. Make sure the monolight is not set to use its optical slave for firing.

Now, when you press the shutter button on the camera, the AlienBee should fire. Because you have cabled the receiver to the light, the only thing your camera can tell the light to do is when to fire. All settings changes need to be made on the monolight directly through its own controls.

Alternatively, you could switch from the PocketWizard triggers to Paul Buff's Cybersync triggering system, and, depending on which triggers you choose, you could regain remote power control over the monolight. Or consider eventually moving to the Godox system, which has sort of replaced Buff as the low-cost system of choice.