Here are the important reminders before changing the exe’s of pRO:
Always Backup your exes
Always Backup your latest folder of pRO, for the latest patch

Download the following

Stripper (for unpacking the .exe)
XVI32 (for hexing the unpacked .exe)

Here are the steps on unpacking the .exe’s

Download Stripper v2.07 After downloading, extract the file and open the stripper.
Click open then locate your exe then click unpacking. The exe must be inside your Ragnarok Folder while unpacking.
After unpacking open your Ragnarok Folder and there will be a file, named _valexe
Delete the original valexe
Rename your _valexe to valexe
Ready to Hex Your Client.

Here are the steps on hexing the .exe’s

Download XVI32 and extract the file
Click open then locate your UNPACKED exe (example valexe)
Press ctrl + R, a window will appear.
The 1st text box is for the "search code" then the last is for the "replace code"
Use the codes below for hexing and click "Replace all". 
After all codes have been replaced, save your work (ctrl+s) and your ready to play.



Here are the codes for hexing the .exe’s

Codes for the server of:
New Chaos, New Loki, Valhalla and Valkyrie

Disable Game Guard:
Search: E8 DF 47 E4 FF
Replace: 90 90 90 90 90


Codes for the server of:
New Iris

Disable Game Guard:
Search: E8 57 F6 FF FF
Replace: 90 90 90 90 90


Opening Multiple Client:
Search: 85 C0 74 07 C6 05 30 F0 85 00 01 53 33 FF 6A 77
Replace: 85 C0 EB 07 C6 05 30 F0 85 00 01 53 33 FF 6A 77

Search: 85 C0 0F 85 CC 01 00 00 0F BE 05 42 21 7B 00
Replace: 85 C0 90 90 90 90 90 90 0F BE 05 42 21 7B 00

Search: 85 C0 74 09 5F 5E 32 C0 5B 8B E5 5D C3
Replace: 85 C0 EB 09 5F 5E 32 C0 5B 8B E5 5D C3

OR you can download here: 
(Mediafire) New Chaos, New Loki, Valhalla, Valkyrie and New Iris

Disclaimer: Use at your own Risk...