This isn't as straight forward as you may hope. As older modular homes and mobile homes settle when the cinder blocks sink into the ground, the house is allowed to "adjust" to it gradually. Start putting jacks under it and lifting to level the home can create issues inside the place. Cracks in walls, doors that don't close, etc, etc.
I would think any mobile/modular home place would have a list of contractors they have used in the past for setting new homes. Granted, I think code nowadays may require the setting of concrete pillars instead of cinder blocks. These may require a person to temporarily move the home in order to pour the concrete.
Been there done this in the past. It's not a lot of fun, but it's not overly complicated either if you just want to use the existing cinder blocks (and add a few while you are at it). Get a couple of large hydraulic jacks (10-12 ton will suffice) and a 3 ft long level and figure out where it needs to be lifted. Lift slowly and incrementally, maybe a one to two inch lift at a location before moving on to the next to help minimize problems.