What you want to do is first off, get all the bits sorted out in the order they will be fitted and note the orientation, this is best done the night before (I did) as you can stuff the crank and bearings into a bag/clingfilm and stuff it in the freezer overnight.
Once you start there is no stopping, so. Get the cases nice and hot, don't worry about melting anything as long as you are using a heat gun you will be ok. Iron hot was the description i was given (as in your spit wont stick).
Once you have the cases ready nip in the house and get the bearings from the freezer if the cases are hot enough they should litterally drop in no violence required at all. Now keep heat on the cases and let the bearings grow into place as the temps stabalise. Once the bearings are fixed (and putting them in this way they will be) heat everything right up again and pop the seals in the same way, they will also drop straight in. Dont forget the output seal and bearing.
At this point i went and got the crank and then proceded to give the left hand bearing a good warming and then slid the crank through, it should slide easily if you have enough heat. There you go, easy. It really is done in about tem minutes with some slightly singed fingers.
When you put the cases together (DON'T FORGET THE O RING ON THE RHSIDE OF THE CRANK) use the heat gun to warm the RHside bearing centre and the cases will slide together much easier.
Oh crank bearings, lettering faces the rod, on the seals the lettering faces away from the rod. And dont mix up the seals or bearings they look similar but ARE different and can be swaped inadvertently.
Hope this helps.