KMaster the method I used was the following. It can be done with mental guesswork via hex editor alone, however unknown values are a challenge. Fortunately you can use the error strings to trace them back. The render distance I had to keep modifying values until I got the intended result, vertex limit I needed IDA because no-one appeared to know the exact number. Note this is not the method currently employed on 4x4EvoR, as of patch 003 and beyond.
There are two methods that I know to use without source code:
1. Guess and check. (Tedious, need to know the value)
2. Use IDA to reverse engineer it, and find said value using a solid reference point.
3. Combination of both. (Find the value by guessing, get more information about it in IDA)
-IDA 5.0 Freeware (Used to breakdown the game executable)
-Any hex-editor of your choice
How I found the vertex limit:
1. Open Monster.exe in IDA, wait for it all to process
2. Search for the error message (Text search)
3. Use this string to find the comparison command, the value should be next to it. (I don't know assembly, terminology could be wrong)
4. Use the hex viewer to determine the offset in the .exe that needs changed.
5. Open the hex editor and change the value to a usable amount. High values will cause crashes.
The example below is for the environment mapping issue with high poly trucks.