I don't own a Kinesis but since I'm only aware of the Advantage supporting foot pedals I would guess you refer to that one.
After taking a quick look on their website
which also features the manual
I found the part you quoted...
Customizing a foot switch action
If you have a single Kinesis foot switch, you can use it to “shift” the embedded keypad to the
active state. If you have a Kinesis Triple Action foot switch the other default actions are Shift
and Keypad Enter. You can also customize any foot switch just like it was another keyboard
Remapping the Keypad Toggle action
The Keypad Shift action cannot be moved or copied to another location. However, a Keypad
Toggle action can be created by remapping if you have a foot switch. Remap a key or pedal
twice using the Keypad Shift pedal as the source action. Start with the keypad LED off, then
remap again after tapping the Keypad function key to activate the embedded layer.
It sounds to me that as stated in the manual:
'The Keypad Shift action cannot be moved or copied to another location.'
Meaning there is no way of remapping keypad toggle to caps-lock i guess unfortunately.
'However, a Keypad Toggle action can be created by remapping if you have a foot switch.'
Meaning altho you can't remap it on the Keyboard itself you can remap it to the foot pedal input if used I guess.
To your other question,
I would very much believe that the foot pedal just connects two contacts to register, so you could most likely imitate a foot pedal by using a jumper between the two correct pins.
So altho you for example couldn't remap keypad toggle on the keyboard itself, you could DIY a single external switch or connect a switch tester to the foot pedal input.
This could then be used for the functions otherwise only available to be mapped to the foot pedal to my understanding.