Both are by @Shirubaurufu and have been pins in the Discord for quite some time:

How to Set the Seed

To change the seed go to: Users(user)\AppData\Roaming\SCP Secret Laboratory\config\nondedicated\config_gameplay.txt You can find this folder by pressing the windows key and r and then entering %appdata%

Then find "map_seed: -1"

If you don't have the nondedicated folder, try starting up a local server and the game should automatically create it for you.

Megapatch 2 and Scopophobia Pre-10.2 Offline Escape seed: 908272117

Scopophobia Pre-10.2 Offline Nuke seed: 875699985

Scopophobia 10.2+ Offline Escape seed: 1919595114

Scopophobia 10.2+ Offline Nuke seed: 1924398478

Scopophobia 10.2+ Femur Breaker seed: 1539875896

Death seed: 1878550827

How to Make Yourself an Admin

To make yourself an admin on your private server you need to go to: C:\Users(User)\AppData\Roaming\SCP Secret Laboratory\config\nondedicated\config_remoteadmin.txt

Then you need to find your Steam64 ID (A common way to do so is to use https://steamidfinder.com/) and replace the template in the file so it looks something like this: