I'm a bit late, but you can use AutoHotkey. I made an AutoHotkey script that will remap WASD to the arrow keys while the SMBX or PGE editor is open. You can pause the script with F11.(For doing anything text-related in the editor)
It'll also include a few cheat hotkeys which can be used with Shift+1-9.
SMBX Hotkey Script
AutoHotkey Download
Download AutoHotkey and run the script, and you should be good to go. If you want to run the script on startup,
read this. Throw the script into the startup folder.
This is probably not the best or easiest way to do this, but it works for me. It's nice to be able to use cheat codes on the fly anyway.