10.3 installer not working

[Perry Hutchison]

How do I get the 10.3 installer to allow me to:

* Edit the default partition sizes, without having to delete and
  re-create them.  I finally figured out how to get into the details
  part of the screen after selecting Modify -- it's not obvious, and
  there doesn't seem to be any help available -- but the partition
  size seems to be immutable.  (I want to make the swap partition
  larger than the default, and the root partition correspondingly
  smaller.)

* Start the partition editor with the existing disk layout.  Having
  once gotten through the hell of getting the disk partitioned the
  way I want it, only to have the installation fail later on, I see
  no reason to have to repeat the partitioning step.  Where is the
  option to read the existing partition sizes into the editor?

* Ignore a minor error and continue.  It complained that it could
  not extract the timestamp of some file -- I don't remember which
  one, and it doesn't matter -- and then the only choices provided
  were to start over or exit.  That is not reasonable.