No scanner needed, just 4 inches of wire.
I presume you are correct in that the problem is most likely the bonnet switch. The problem is common and replacing the switch is the most easy solution providing that is the problem.
The bonnet switch is located on the right hand front corner bonnet latch which you probably already know. There is an electrical connector attached to the switch; the latch on the left side, no electrical connector.
The electrical connector feeds back to the alarm system. The link just below is to a pdf explaining the alarm system. See page 9 of 17 re the bonnet switch.
http://bit.ly/1a1x5ni
This link is to a number of files within my alarm album which you may find of interest as well.
http://bit.ly/147Vmma
To determine if the switch is the problem, disconnect the connector from the switch.
Leaving the bonnet open, attempt to lock the vehicle. I expect the horn will beep as when a door is not properly closed.
Then with a short piece of insulated sheathed stranded electrical wire, jump the two pins in the connector attached to the vehicle harness. Now this time I expect the vehicle will lock and with no horn sound.
If so, then the problem is probably the bonnet switch.
Incidentally, if you read page 9 of 17 re the bonnet switch, you will realize I have the above instructions reversed to what page 9 indicates. I think the page 9 explanation is wrong and I am right but regardless, disconnecting first and the secondly jumping the wires will tell a story.
I am pretty certain I am correct re jumping the wires will make the system think the bonnet is shut, if not then no jumper and as follows. Drive around for a few days and see if the problem continues. If not, then the switch requires replacement, a do it yourself task.