I suppose the effect Charisma will have depends on what your new AI script is going to do. I think what you want is to improve the Saving Throws of the enemies...?

All this can be done with KotOR Tool.

I'm dynamically increasing enemies' stats based on your character level and the original value of the stat for each npc. Essentially i'm making AIs harder in every respect, and i'm using items as a workaround to increase stats by more than 20.

code:--------------------------------------------------------------------------------
object oItemBooster1=CreateItemOnObject("uti_templateresref1");
object oItemBooster2=CreateItemOnObject("uti_templateresref2");
object oItemBooster3=CreateItemOnObject("uti_templateresref3");
object oItemBooster4=CreateItemOnObject("uti_templateresref4");
ActionEquipItem(oItemBooster1, INVENTORY_SLOT_CWEAPON_L, TRUE);
ActionEquipItem(oItemBooster2, INVENTORY_SLOT_CWEAPON_R, TRUE);
ActionEquipItem(oItemBooster3, INVENTORY_SLOT_CWEAPON_B, TRUE);
ActionEquipItem(oItemBooster4, INVENTORY_SLOT_CARMOUR, TRUE);
--------------------------------------------------------------------------------

In this block of code, how do I reference to the name of my new uti files? do I just put:
object oItemBooster1=CreateItemOnObject("uti_filename");

?

Technically, you put what is in the TemplateResref field of the .uti, but that is supposed to be defined as the name of your uti file (minus the .uti extension).

That's the long answer for 'yes'.

Once the item exists in-game, you can refer to it by its Tag using GetObjectByTag function.