Take a look at the "Actor" component within the file "actor.str". Around line 105, you'll find the "acMaxWound" field, which tracks the maximum number of wounds the character can sustain. During the Setup phase at priority 1000, the Calculate script initializes the value of the field. The field is not other used until the Final phase or later. So all you need to do is modify this field via script between those two timings.
The simplest way to handle this is to add a permanent adjustment. Copy the "Skill Points" adjustment and create your own "Maximum Wounds" adjustment. All you need to change in the script is the line that applies the adjustment. Replace the "#resmax[resSkill]..." line with the following:
Code:
herofield[acMaxWound] += field[adjUser].value
Unless I'm overlooking something here, the above ought to establish an adjustment that can be easily used on any character/monster/whatever to adjust the number of wounds.
Hope this helps!