EDIT_ Since you got them off before I finished this post I dunno if this info would have helped......
I believe you have to remove the wheel hub retaining nut.
From my Ford Service CD:
Vehicles with rear drum brakes
CAUTION: The wheel hub removal in this procedure is for installing new wheel bearings, not for access to brake system components.
(This will remove the drum but not give you access to remove the shoes or other brake components- Ian)
Remove the wheel and tire. For additional information, refer to Section 204-04 .
Release the parking brake.
CAUTION: Use a socket to remove the wheel hub retaining nut to prevent damage.
Remove the wheel hub.
Remove the wheel hub retaining nut.
Installation
Vehicles with rear drum brakes
CAUTION: Avoid any impact on the wheel speed sensor ring.
CAUTION: Make sure the wheel speed sensor ring is clean.
CAUTION: Avoid any contact between the wheel speed sensor ring and a magnetic surface.
CAUTION: The wheel hub retaining nut can be re-used four times, mark the wheel hub retaining nut.
NOTE: Do not fully tighten the wheel hub retaining nut at this stage.
Install the wheel hub.
CAUTION: Rotate the brake drum 10 times in the opposite direction when tightening the wheel hub retaining nut to prevent damage to the bearing.
Tighten the wheel hub retaining nut.
Apply the parking brake.
As for removing the 4 bolts.....
Brake Drum
Removal
All Vehicles
CAUTION: The brake drum removal in this procedure is for access to brake system components, not for installing a new brake drum
NOTE: To install a new brake drum, refer to Wheel Hub in section 204-02. (Like stated above- Ian)
Release the parking brake.
Remove the wheel and tire. For additional information, refer to Section 204-04
You may be thinking of the old-style of brake drum, which goes over an axle with 4 (or 5) lugs in the axle and 4 (or 5) holes in the drum. On the Focus, the wheel lugs are part of the brake drum.