Prior to installation
In Windows Features ensure .net framework 3.5 is added
Installer requires scenery.cfg, so copy to main p3dv3 folder from %programdata%
During installation, say no if asked to fix FSX registry entry

IOM
Installation can now be run as normal from DVDs
Error the specified path '' is unavailable, fill in the path to P3D installation folder
In case of issues / alternative methods
Copy all files from DVDs into one folder
Use 7-zip to extract ESI-I1.cab into one folder
Run Isle_of_Man_Download.exe will create an Isle_of_Man_Download.esi (19GB) file.
Install the esi installer (if not already) installed.
Should have 5 esi files which can be used to install.
Right-click Isle_of_Man_Download.esi and select install to install the scenery.
Move scenery.cfg back to %programdata%.
Earth simulations software can be uninstalled from computer. This doesn't uninstall the scenery. Installer leaves backups of changed files.
Scenery.cfg additions
[Area.182]
Required = FALSE
Active = TRUE
Layer=182
Local = D:\P3DScenery\ES-SFX
Title = ES-Sound-Effects-Library
[Area.183]
Required = FALSE
Active = TRUE
Layer=183
Local = D:\P3DScenery\ES-3D
Title = ES-3D-Library
[Area.184]
Required = FALSE
Active = TRUE
Layer=184
Local = D:\P3DScenery\ES-IOM-Terrain
Title = ES-IOM-Terrain
[Area.185]
Required = FALSE
Active = TRUE
Layer=185
Local = D:\P3DScenery\ES-IOM-Photo
Title = ES-IOM-Photo
[Area.186]
Required = FALSE
Active = TRUE
Layer=186
Local = D:\P3DScenery\ES-IOM-3D
Title = ES-IOM-3D
[Area.187]
Required = FALSE
Active = TRUE
Layer=187
Local = D:\P3DScenery\ES-IOM-SFX
Title = ES-IOM-SFX
[Area.188]
Required = FALSE
Active = TRUE
Layer=188
Local = D:\P3DScenery\ES-IOM-TFX
Title = ES-IOM-TFX
[Area.189]
Required = FALSE
Active = TRUE
Layer=189
Local = D:\P3DScenery\ES-IOM-FX
Title = ES-IOM-FX
[Area.190]
Required = FALSE
Active = TRUE
Layer=190
Local = D:\P3DScenery\ES-IOM-Airports\ES-EGNS-Ronaldsway
Title = ES-EGNS-Ronaldsway
[Area.191]
Required = FALSE
Active = TRUE
Layer=191
Local = D:\P3DScenery\ES-IOM-Airports\ES-IOM-Helipads
Title = ES-IOM-Helipads
[Area.192]
Required = FALSE
Active = TRUE
Layer=192
Local = D:\P3DScenery\ES-IOM-Airports\ES-X9AN-Andreas
Title = ES-X9AN-Andreas
[Area.193]
Required = FALSE
Active = TRUE
Layer=193
Local = D:\P3DScenery\ES-IOM-Airports\ES-X9JU-Jurby
Title = ES-X9JU-Jurby
[Area.194]
Required = FALSE
Active = TRUE
Layer=194
Local = D:\P3DScenery\ES-IOM-Airports\ES-X9MR-MountRule
Title = ES-X9MR-MountRule
TODO: Add list of changed files.