Open your module in your hex editor.
Press Ctrl + R, and the following window will appear.
Alter it to the following settings.
Next, you'll enter the following into the "Search for" bar.
XXXX = Old Sub Action Count.
38A0XXXX
In my example's case, I'll be entering 38A001DE
You'll then enter the following into the "Replace with" bar.
XXXX = New Sub Action Count.
38A0XXXX
In my example's case, I'll be entering 38A001E2
Once you have both fields filled out, click on "Replace All" before the following window appears.
Click "OK", save, exit your hex editor, and make any desired PSA edits to use your new Sub Actions.