There is an adjustment in the community pack just for that. (COM_5ePack_PHB - Adjustments.user) - "Casting Attribute"
In the tutorials in the Help file for the editor, there's an example of how to give spells to a non-casting class - it should be the same general method, just have to overwrite the original attribute at the correct time:
Code:
perform linkage[table].setfocus
doneif (state.isfocus = 0)
~ Spellcasting attribute
perform focus.setlinkage[castattr,BaseAttr,"IsAttr.aINT"]
or more directly:
Code:
~ Set spell casting attribute
perform hero.childfound[cHelpPal].assign[SplAttr.aWIS]