Hi!
I've been experimenting and I think I can get something similar to the V-Ray RT trick using Octane's native maps. Try the following:

1 - Add a 
RGB Image map to the materials maps slots, e.g. diffuse. 
2 - Add a 
XYZ to UVW map to the RGB Image map's 
Projection slot.
3 - Change the XYZ to UVW map's 
Coordinate Space to 
World space
4 - Add a 
3d Transform map to the XYZ to UVW map's Transform slot. 
5 - Change
 X Rotation to 
-90
6 - You can now use the remaining Rotation, Scale and Translation settings to position the map where you need it. 
Here's how this looks with a UVW template applied. 

I hope that helps, please let me know if you have any further questions.
Many Thanks,
Paul