While searching for solution around install.ps1 I quickly realised that the edit file -> create package -> publish -> update target cycle isnt very handly. There are step-by-step instructions on the net how to debug install.ps1, but when I tried to use them I run into new problems about incompatibility between my packages and nuget powershell cmdlets.

So I used a poor mans solution instead:

1. Add some dummy content file to You package.
2. Install Your package.
3. Edit that dummy file (each next package install cycle will ask You about overwriting and that is what we need!)
4. Open Package Manager Console (PMC) in VS
5. Execute “Set-PsDebug -trace 2”. It helps You later.
6. Open the install.ps1 in some editor (I used PowerShell ISE) from target project’s packages directory.
7. In PMC run “update-package _yourpackagename_ -reinstall”. The installation will stop because file overwriting.
8. In the PS editor edit and save install.ps1, but dont close it.
9. Back to PMC and answer the overwriting question (with ‘L’ or ‘N’ to keep the modified file).
10. See the results.
11. Go to 7.

Not to smart, didnt uses tools and libraries but it works in acceptable cycle time.