First think I would do is to make sure I have an exploded parts diagram of the engine block. that way you know how it comes apart and how it goes back together.
The cases are sealed with basically thin silicone so they're stuck together pretty well. What I've done in the past is thread in a few of the bolts and tap on those with a rubber mallet (or dead blow hammer) and separate the cases.
The manual actually says..."separate the crankcase halves by installing to of the cap screws in opposite corners...using a plastic mallet, tap on each cap screw until the halves separate."
hope that helps! good luck