Generally speaking the cartridge bearing hubs are about as simple a construction as you will find.
Dismantle as follows(I will generalize some points since I don't recall the exact model)
1. Remove the outer cap/spacers. They usually look like cones and have an allen set screw on them. Loosen that and they should slide off the axle, exposing the outer faces of the cartridges. Make sure there are no other locking devices, such as lockrings in place before proceding.
2. Support the wheel on a surface such that the axle is not contacting and that it is solid. Place a hardwod block on the end of the axle and hit sharply with a hammer. It should pop right out. Flip it over and repeat for the other cartridge.
3. If you are buying new bearings, then procede to installation. To repack, do the following:
On Sealed Cartridge, it will have a rubber coated sheet metal cover. The cover is easily and savely removed with a hobby Xacto knife point. Insert on the axle face and gently pry outward, being carefull not to warp it. Do so to both sides of the cartridge and spray liberally with Brakleen or similar fast-acting solvent. Do so until clean and let dry. I only repack cartridges with Valvoline #614 red moly grease. It has proven itself superior in several commercial applications I have had. Rotate the bearing as you pack it very thoroughly with the grease.
Ensure the covers are perfectly flat before installing them, as a warp can induce a minor drag. Press evenly and slowly to work the air and excess grease out of the bearing and wipe it clean with a clean rag.
4. To install:
Again, generally the installation will go as follows. Insert the axle into one cartridge. Slide it into the hub assembly and slide the other cartridge onto the other end. Slide the outer spacers onto the ends of the axle and insert the axle skewer. Tighten the skewer until there is no slack, then close it. Open it and take up the slack. Repeat until you cannot take up the remaining slack, then add spacers to the ends of the axle(nuts, washers etc.) and tighten it successively until it bottoms, which you will feel. Leave it tightened on the last time, and tighten the set screws on the spacer cones. Remove the extra spacers and voila, it is done.
As far as replacement cartridges goes, you can get them from the bike mfg, but I wouldn't. For the same price, go to a commercial equipment supply company and get top notch NTN brand bearings. They last over 6 times as long in our large motor driven equipment. I have worn out stock units in as little as 2k miles, but the NTN have 4k and counting. You will however have to bring samples along, as they would be cross refferencing.