OK, here are the spoilers and the way how I smacked Kangaxx EASILY yet again:
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First, you need Kangaxx's arms and legs and Kangaxx's torso. There are 2 spots where these are: 1 place is in the Unseeing Eye part of sewers, where the Sassar is (on the way down to Amaunator Temple). In the sarcophagus there is one lich with one part(s). Another lich is in Bridge District, near the Twisted Rune hideout, also near there is the place where you did the "Buried Tirdir" quest. The door to lich (as well as to Twisted Rune) is trapped though, disarm it first. I aint going into lich killing ways, it is't hard;
Second, Kangaxx. You take the bones to him, he is in Docks District near the Mae'Var guild hall. Mind the trapped door again. You need to kill Kangaxx 2 times, first in his lich form and then in the demilich form. Latter is more peskier.. In any case, here as the buffs used by me on the party:
Bless;
Chant;
Defensive Harmony;
Resist Fire/Cold;
Haste;
Draw Holy Might (main char cavalier, Anomen);
Weapons used by the party:
Carsomyr +5 (main char cavalier);
Sling of Everard +5 (Jaheira, bought from Deidre in Adventurer's Mart (bonus CD merchant));
Azureedge axe (Minsc, axe wasn't much of use against demilich tho);
Flail of Ages +3 (Anomen, useless against demilich);
Sling of Seeking +2 (Aerie, useless weapon in this case);
Jan's X-Bow (forgot the name, useless here anyway);
So all in all, only 2 weapons could hit the demilich

Casters in this case, like Aerie and Jan, can use Melf's Minute Meteors, these work like a charm on demilich.
And that's it. These Fire resist is naturally needed due to Fireshield and some blasts.. Other buffs were used mainly for the bonuses to rolls (to party) and penalties to the enemies. All these spells are relatively low level and should be acessible to most, if not all. During the combat I used also the Secret Word and Breach to remove the pesky protections, one of each. Also, if you have a thief in the party (and you should), set the traps to the sarcophagus - the lich will spawn on the traps and will get whacked by those even before his spell triggers will launch, thus he will get quite a whack up his... back right at the start. Yoshi's traps are best, but Jan's will also do (if you're not the thief yourself).
Before you get down to Kangaxx buy all the Protection from Undead scrolls you can. Good thing is to get at least 2 per face. Better safe then sorry. Share the scrolls out to party members and set them to Quick Slots, but DO NOT use them while Kangaxx is in lich form. Not needed simply.. Also preferrable is to have the clerics in the group to have the Summon Skeleton memorized, preferrable the clerics being over or at lvl 15 (for the skeleton warriors

) But do not summon them yet for the Kangaxx in lich form.
Anyway, the killing: by the time the demilich appears, most if not all of your buffs are gone. Ran out and got dispelled. No biggie. Just before Kangaxx the lich is about to die, he will throw a speech. Immediately pause the game and use with everyone BUT MINSC the Protection from Undead scroll. As soon as the scroll is used, let the Aerie and Anomen (let's say clerics) cast the Summon Skeleton between the almost dead lich and the main char in this case (cavalier with Carsomyr). Idea is that the skeleton warriors appear BEFORE the demilich and the main char is behind the skeleton warriors, just in case (reason is that the mobs usually go ballistic on the FIRST target they see, so the idea is to make the expendable summons to be the first things to see). Minsc has too low WIS probably to cast the Protection from Undead scroll, so let him Enrage. By this time the skeleton warriors are summoned and the main char has, together with others, has probably killed the Kangaxx in lich form. Now the demilich appears and here's the reason WHY Minsc has no Protection fron Undead on yet - IF all are not visible to demilich when it spawns, it cannot speak to anyone and will be thus UNKILLABLE! In current case he doesn't see anyone else but Minsc and so he speaks. After that he proceeds to Imprison, but the skellies first because these are closer. That's 2 spells it has to cast and by that time, Minsc can get the Protection from Undead from any nearby char, who has the extra scroll on him/her.
Demilich finishes the skeleton warriors by Imprisonment, but after this he just stands there and clicks the jaws, because he doesn't see anyone else - all are protected from undead and invisible to him. Take off Party AI, stop everyone save your main char with Carsomyr (in this case) and Jaheira (or anyone else) who has the Sling of Everard. If someone has any other +4 or better weapon, can send them in as well. And whack away. Soon it's dead and tadaa! XP rolls in.
Sorry if that got to be a bit lenghty post

But the idea was to show that you can do it easily, with just some lower level spells (in the first fight, they would be useless in the fight with demilich anyway) and with the gear you can get by that time. Unless you rushed to Kangaxx, you should have all this gear and the levels to cast Skeleton Warriors. However, you can use ANY summon here. The idea is simply to buy some time while Kangaxx the Demilich makes it's speech (he simply MUST MAKE THAT SPEECH) and starts Imprisoning. Summons do here just fine and will buy the time needed. I have killed the Kangaxx like this few times, it only takes some little planning
[ 12-18-2001: Message edited by: Whailor ]
[ 12-18-2001: Message edited by: Whailor ]
[ 12-18-2001: Message edited by: Whailor ]