Before removing the bolts, inspect their holes. Like the CAT 314E, machines from John Deere, Hitachi, and Volvo feature slotted holes (located further in, toward the cab), making your job much easier.
Just loosen the bolts from the slotted holes and remove the others. Then, you can slide the belly pan out to remove it and follow the same steps for installation, instead of holding the pan while trying to put the bolts back in.
Next, grab an empty bucket or pan to catch the oil. Depending on the make and model, you may need more than one drain pan.
Another thing to consider is the type of drain. The CAT 314E has a needle valve with an attached hose piece. Other machines, like the Komatsu PC200LC, have a ball valve or a simple plug, as in the case of the John Deere 85G. Be careful when removing the drain plug. As soon as it comes out, oil will pour out.
Wait for the oil to drain completely, then close the valve and reattach the belly pan.
(Note: Looking closely at the pictures, you will see Keith wearing gloves. Other mechanics prefer PR88 cream for dexterity or if working in tight areas where sharp edges can tear rubber gloves.