While Buildable Units was made and balanced with LWOTC in mind, it can work without it. It takes a little bit of config work on the user's part, which can be done in a program as simple as Notepad. Here are the steps to use hectorzx's Advent Drone mod with Buildable Units:

1) Go into Buildable Units' XComBUOptions.ini
2) Find [BuildableUnits.BU_AdventDrone_Tech]
3) Comment out (put a semicolon in front of) these two lines:
+AdventDroneTech_RequiredTech = "AutopsyDrone"
AdventDroneTech_RequiredCorpse = "CorpseDrone"
4) Uncomment (get rid of the semicolon in front of) these two lines:
;+AdventDroneTech_RequiredTech = "AutopsyDroneH"
;AdventDroneTech_RequiredCorpse = "CorpseDroneH"
5) Repeat the previous 3 steps for [BuildableUnits.BU_HunterDrone_Tech] and [BuildableUnits.BU_EnigmaDrone_Tech]
6) Save those changes.
7) Go into Buildable Units' XComClassData.ini
8 Find all instances of "LWDroneMeleeStun" and replace them with "DroneHMeleeStun"
9) Find all instances of "LWDroneShock" and replace them with "DroneHShock"
10) Find all instances of "LWDroneRepair" and replace them with "DroneHRepair"
11) Save those changes.

Note that when I do an update, configs may be reset, so refer back to this thread or make backups as you deem necessary.