Upgrade: execute action before RemoveExistingProducts

[Rimidalv_Veigro]

I am developping a msi which has to upgrade from version 1.1 to 2.0. But I need to do some actions reinstalling the old version - modify some registry keys in HKEY_LOCAL_MACHINE and unregister some DLLs. I am putting an immediate action, which does these routines.
If I run the installer with a non-admin user, the Immediate action cannot modify registry keys or unregister DLLs. Only actions in system context can do that.

Immediate actions in system context are not supported.
I have to puct the actions in that order:

.....
InstallInitialize
MyCustomAction
RemoveExistingProducts
......

MyCustomAction is the action, which does these system routines. But it's not allowed to put system context action before RemoveExistingProducts
I have to

[Kevin_L]

I think that only Deferred Execution Custom Action can be set between InstallValidate and InstallFinalize.

Immediate Execution Custom Action must be set before InstallValidate or after InstallFinalize.

[Rimidalv_Veigro]

^ Yes, I know that very well. But I want top put my custom action between InstallInitialize and RemoveExistingProducts.
Also I need to enable my custom action to have system privilegies.

Thanks in advance