Here is the unit break down along with 3 Talos that I have been using.
For tactics I have been using with these, please refer to this article.
http://natfka.blogspot.com/2011/06/haemonculi-refinement-with-grotesques.html#more
As for the rest of a list, just add and fill in what you want. This unit will out survive the rest of your army, and I use it as a focal point to push into enemy lines. At 2500 pts, (what I normally play), even heavy shooting armies tend to lack the firepower to destroy this unit. Just make sure you use a maximum spread and be aware of S10 large blasts.
1 Asdrubael Vect @ 240 pts ((C:DE, pg. 55); Unit Type: Infantry; Fleet; Night Vision; Power from Pain; Independent Character; Fearless; Master Tactician; Ancient Nemesis; Ghostplate Armour; Haywire Grenades; Plasma Grenades; Shadow Field; Splinter Pistol; Obsidian Orbs; Scepter of the Dark City)
1 Haemonculus Ancient @ 225 pts ((C:DE, pg. 85); Unit Type: Infantry; Night Vision; Power from Pain; Independent Character; Altered Physique; Gnarlskin; Close Combat Weapon; Splinter Pistol; Casket of Flensing; Webway Portal x1)
1 Haemonculus (Night Vision; Power from Pain; Independent Character; Altered Physique; Gnarlskin; Close Combat Weapon; Splinter Pistol; Shattershard; Webway Portal x1)
2 Grotesques @ 140 pts ((C:DE, pg. 86); Unit Type: Infantry; Night Vision; Power from Pain; Altered Physique; Berzerk Rampage; Bulky; Gnarlskin; Close Combat Weapon; Liquifier Gun)
1 Aberration (Close Combat Weapon; Scissorhand)
3x 1 Talos Pain Engine @ 135 pts ((C:DE, pg. 92); Unit Type: Monstrous Creature; Night Vision; Power from Pain; Fearless; Move Through Cover; Random Attacks; Armoured Carpace; Chain-flails; Close Combat Weapon x1; TL Heat Lance)
Total Roster Cost: 1010
To answer some of the questions from previous commenters.
Abuse Puppy: I prefer Venom Blade on the Aberration
The truth is, a Venom Blade is an excellent choice for this unit. It is cheaper with one less attack than with scissorhands. Why I use Scissorhands is that against most opponents (marines) I need the extra attacks to kill some models. A 3+ with a poison re-roll will give you more wounds simply because it doesnt matter whether or not you are re-rolling a 3+ or a 2+. Scissorhands are 10pts more though, and if you have to cut down points, here is a good place to do it.
Mercer: Only thing is I am not sure is the anicent as only a little bit better than a normal Haemonculus but costing a fair bit more.
I have used regular Haemonculi many times with this set up, and once this unit really starts getting hammered, the Haemonculi will die before the Grotesques. So I find it very helpful to have that extra wound. Also when counter assaulted by independent characters, your Haemonculi often will get singled out and destroyed right away. Having an initiative of 5 with an agonizer really helps keep this unit alive in a counter assault. If you lose your Haemonculi, and Vect takes a pain token with him elsewhere, you do not want to lose your haemonculi leadership. The abberations leadership is 4.
It also happens a lot that people avoid the area where your portals are, I mean who wouldnt want to stand in the path of 3 talos, Vect, and a unit of Grotesques. Having a BS5 on the greater Haemonculi give a Casket of Flensing the rolls to hit it needs. The Casket of Flensing adds an additional punch to this unit, that most people are not ready for. If it doesnt work with the random dice, so what. Hitting on a 2+ makes the casket worth taking.
Between the Casket of Flensing, a Shattershard, and the Grotesques, this unit will hold its own long after Vect has left the unit on his rampage of death.
As far as Vect goes, he is a monster in close combat. He also helps insure that I am able to get field position for launching my Talos reinforcements out of webway portals. I can't tell you how often Vect has slaughtered massive amounts of the enemy, he is brutal against anything the gets a hold of (with the exception of dreadnaughts.... : 0 Dan) His record is 2 5-man Devastator Squads, a Librarian, a Sanguinary Priest, and 2 5-man Assault Squads in one game vs Blood Angels.
I am sure there are other ways to field units like this, however, this is what I have found works best for me on the tabletop. They are just so hard for opponents to take out.