[Kestrel Daystar]

Hmmm, well. Here are my thoughts on how to make a 'GOOD' aligned alternative. You may not like them, and I won’t be offended, so please be brutal by all means:

After finding and delivering Renfeld to Rylock at the harpers hold, Rylock thanks you for returning him.
After going into the hold, Xzar approaches you, and asks you to go and find Montaron.
Now, rather than sneaking into the Harpers Hold and the harpers using you to kill Xzar without you knowing, they tell you their plan on how to dispose of the Zhent necromancer straight after Xzar approaches you. Rylock tells you that you could aid the harpers rid Athkatla of Xzar or side with Xzar and the harpers become hostile towards you (which would mean Jaheira leaves the party).
Rylock explains that there would be no reward for siding with the harpers, but it is the right thing to do. Siding with Xzar however would be profitable and you would have chance to get Montaron back, be paid and have both Monty and Xzar as NPCs.
If you go through the good path and help the harpers, at the end, Rylock explains that this was all a test to see where your loyalties lie.
He then goes on to explain that their is a reward for helping the harpers after all; passage to Spellhold, for a mere 10,000gp and a few tasks completing (maybe involving more Zhent). There would then follow a number of tasks you need to carry out until you are allowed to travel to Spellhold.

Saemon would still be the guide to Spellhold (seeing as noone else would dare the voyage, and especially at such a low price) and everything would continue on from there as it usually does with the Shadow Thieves or Bodhi.

These are just rough ideas obviously. You guys will probably have better ones to add.

Tell me what you think

--Kestrel--