Fabione

Hello everyone,
I was wondering if there is a way to set the ELS cruise lights always on for the npc patrol cars of lspdfr, so that when they spawn around the map they have the steady cruise lights activated as happens in the reality in my country.
I tried to search in the ELS user guide or other forums but I didn't find anything.
 
Thanks in advance to all those who will help me!

EUP has an LML package already. If you install that version, installing any mod that changes EUP should be as easy as just replacing the default EUP files within its LML directory with the contents of the mod's rpf files.
 
See below image for EUP's LML download: 
 

Specifically, if you open your mod's eup_componentpeds.rpf, you should find a bunch of folders called "mp_f_freemode_01" or similar. You would just extract these folders to Grand Theft Auto V\lml\EUP_L&O_Public\content\stream\peds

I justed tested it myself using the snippet you provided above and it worked just fine, my file got replaced. Log looked like this just so you can confirm:
 
2021-04-19 18:20:45 TRACE d:\gtav\vfs\vfs\vfs\packfilehooks.cpp:242: Global full replace: addonDLC:/islandtest/carcols.ymt 2021-04-19 18:20:45 TRACE d:\gtav\vfs\vfs\vfs\packfilehooks.cpp:242: Global full replace: addonDLC:/islandtest/carcols.ymt  
XML:
<FileReplacement> <GamePath>update:/x64/data/carcols.ymt</GamePath> <FilePath>carcols.ymt</FilePath> </FileReplacement>  

Replacing a single entry is an advanced feature, as it requires some tricks to work behind the scenes. That being said, it is still incredibly easy to use. From what I understand your new vehicles.meta only has one entry which is for "alpha", correct? If that is the case, you can load that vehicles.meta like this:
 
<FileEntryReplacement type="VEHICLE_METADATA_FILE">replace/vehicles.meta</FileEntryReplacement>  
Check out the documentation here under "Single File Entry Replacement" for more information: