This component alters Imoen's "starting files", so it takes effect when you pick her up
in Irenicus' Dungeon, recover her in Spellhold, or summon her in ToB from the fate spirit.
With the exception of the first case, she comes with 5 mage levels and an undone level-up,
so you can decide to preserve that next weapon proficiency for a better future use (when
you have enough XPs to reactivate the swashbuckler class at once).
So, if you already surpassed that 5th level in Chapter 1, you get another chance!
After all, she gets lobotomized, sort of

2)Why and What
Why turn Imoen into a Swashbuckler/Mage?
Because it is a more fitting type of thief for her: more charming, more stylish, and most
importantly one that doesn't learn how to backstab (*that* would be really unfitting given
the story of the main characters!).
On top of this, she should be more fun to play, and slightly more useful in combat.
What are the changes, exactly?
-Starting XPs: They are now 161,000 XPs at the start (end of BG1 + TotSC.)
This means that she starts as a Swashbuckler - exactly at level 10 - immediately dualled
to mage.
She won't really be much help in Irenicus' Dungeon (actually this may make it more interesting,
but hey, she still has Magic Missile!!

-She now has a CORRECT number of points in her thieving abilities. The ones she already
knew have been increased a little, Detect Illusion has been left at zero (well, zero means
zero...). The main difference is in Set Traps. She *can* now try to use them! After all, she
can find and disarm them so well already..
-Weapon proficiencies have been left with a generic distribution. Using future mage-points,
she can play a "stereotypical" dual-wielding swashbuckler (sword and dagger?), or decide to
aim for the traditional Staff of the Magi + Short Bow combo.
But this time she can specialize.
-When rescued at Spellhold, she'll have less XPs compared to the orginal game, and she
will have lost the spells learnt before (this also happens in the normal game).
Bring some scrolls

Imoen still receives a boost in XPs, for the torture and experience she went through but not
as large as in the original game.