Gently bend the Jimmy outwards to pry the crack open a little larger and lift the lower housing up a small amount.
There are several plastic clips on the lower housing that fit into a channel in the aluminum top housing. Your goal is to use the Jimmy to push these clips inward enough to free them from the channel, while gently pulling up on the lower housing.
If your mini does not have Airport installed, then skip this step.
Grasp the Airport antenna board and lift it off of the two plastic posts holding it in place. You may need to push back the black plastic tab jutting through the lower left corner of the board.
If your mini has neither an Airport card nor a Bluetooth board, you can simply lift the optical drive up and away. Otherwise, you need to disconnect the Airport and/or Bluetooth antenna cables first.
With your free hand, pull the Bluetooth cable up from Bluetooth board and unplug the Airport antenna cable from the right of the Airport card. Caution: both of these connections are very small. When re-assembling unit after repair, you may want to remove the two screws holding the airport card to the assembly and lift the card up and out to re-attach the cables.
Use a #1 Phillips to remove the two screws attaching the right side of the hard drive to the plastic framework. You'll need to angle the screwdriver down to get access to the lower right screw. Be sure to apply steady force to the screws and turn slowly so as not to strip them.
Use a spudger to pry the hard drive away from the interface board. Wedge the flat end of the spudger between the interface board and the far right side of hard drive and wiggle back and forth until the hard drive slides out about a sixteenth of an inch. Then move to the other side and repeat the procedure. Go back and forth until the hard drive slides free.
When reinstalling the hard drive, make sure that you don't slide the top pins into the lower row of holes.
While holding the assembly with the speaker resting on the table, remove the four black Phillips screws holding the speaker in place and their associated rubber bumpers.
When replacing the speaker, place the rubber bumpers into the plastic casing first, then slide the screws into them, and finally line up the speaker with the screws. When working on the lower screws, you'll need to angle the end of the screw up a bit, as the speaker sits higher on the framework than you might expect.
The cable you're about to remove is very fragile - do not pull directly on the wires. Instead, try to pry up the connector directly, using your fingernails or a small flathead screwdriver if necessary.
Disconnect the speaker connector from the interface board.