IMHO it is not worth it in NWN as they did not fix the feats to allow for using some of them for monk unarmed damage properly if I remember correctly. Maybe there is a patch I am clueless about though so here goes an idea:
Str: 14
Dex: 14
Con: 14
Int: 14
Wis: 14
Cha: 10
May need to modify if you pick a race with adjustments.
Pump Dex as you level. Higher Initiative, Ref saves and AC are all going to be very useful for you with a base of +2 modifiers in all of the other attributes.
Skills: Focus on Hide, Move Silently, Open Locks, Disable Device, Search, Tumble, and Use Magic Device. The rest should really be if you have extra.
Feats: Weapon Finesse: Unarmed (Think that doesn't work with unarmed strikes as it is supposed to though

)
Ok, now, I lost some of the discs to my NWN game, so I can neither re-install it or play it and therefore cannot test out which feats didn't work properly, so I think I will leave feats alone aside from that. However, I will get into the class breakup.
First off, the NWN games nerfed the monk class. Nothing major, as most of the game revolves around straight survival and killing, but they completely ditched some of the monk class abilities as they didn't use the things they apply to at all in the game. So I will break down what you will gain if you go past 9th level in either class for you then:
Monk:
Level 10: Ki Strike Lawful, +1 to Monk AC (+2 total), +1 BAB, +1 All saves
Level 11: Greater Flurry (3 attacks at full attack bonus + extra based on high BAB), Immunity to all Poisons, +1 BAB
Rogue:
Level 10: +1 BAB, +1 Ref Save, Special Rogue Ability
Level 11: +1 BAB, +6d6 (total)
Now, to put this bluntly, if you are going for a character that can deal damage in melee, you want to go higher in monk. Not only do you get a bonus attack, but you do not lose out on BAB, you get higher HD, AC, Poison Immunity, and a bonus to 2 extra saves, plus a free weapon upgrade. The only thing truly worthwhile that you would be losing is the 10th level rogue Special ability. Without a high Int, the only truly worthwhile and all-purpose one is Improve Evasion, which monks get at level 9 standard.
I would say the real question involved IMHO, is whether to go 13 Monk/ 7 Rogue or 11/9.
If you go for 13 monk levels, you pick up on average 2 extra HP, it evens out with BAB and Saves so the monk wins there by a small bit. You also get +10 to speed, 2d6 unarmed damage, the Abundant Step ability (not sure if/how that works in NWN to be honest. The BIG thing, is spell resistance at monk level 13. That would give you SR 23. Far better than a +2d6 to sneak attacks I think, depending on how you level your character.
However, you would lose out on Improved Uncanny Dodge. SR 23 isn't anything godly as a 20th level character, but it would give moderate protection against mid-level fodder type wizards and sorcerers and the like. I don't know if you deal with many of those in the NWN game. I never played very far into any of the suppliments besides HoTU. It will basically give 13th level wizards/sorc a 50% miss rate however, with their chance of succeeding climbing each level the wizard has higher than 13. This really only becomes important if you decide to go through all of your monk levels first and in one shot or not. If you do your rogue levels first and then monk, it becomes less valuable. Against a 17th level Wizard, it is almost like applying the casting failure penalty of wearing Scale Mail armor or 25% chance of failure. Still, 1 out of 4 spells thrown your way not affecting you could be the difference between life and death. FYI, chances are that by the end of the game, your "fodder" encounters will be near to 17-18th level for the most part.