Hire someone for $50? Egads. If you’re at all friendly with any of your neighbors, ask them if they’d be able to drill that hole.
Wood bits catch on fire if they get too hot. 
Forstner bits are specifically designed to eliminate tear-out, and brad-point bits are great for preventing the bit from wandering. Even spade bits work well for precise drilling, but usually result in large tear-out. Spending money on a forstner bit for one application is probably overkill, though.
This is the add-on I bought:
I had not realised that this product required any kind of drilling. I thought there were pre-drilled holes which I could just simply attach the extension to.
Imagine the shock I had when the first page of the manual was a drill!
http://www.ikea.com/us/en/assembly_instructions/signum-cable-management-horizontal__AA-489805-2_pub.pdf
I feel incompetent actually. Shouldn’t Ikea make it clear that I needed a drill? And you can’t actually access the manual until you open the packaging…
Well that’s a generic extension for any desk. They’re not going to drill holes in all of their desks to cater to every possible addition people might want to make. Seriously, drilling a small hole for something like that is a piece of cake. It doesn’t really matter if its a bit deep or shallow as long as you don’t drill through to the upper surface.
Thanks so much for the assuring comment. You just gave me some courage to try it out!
My brother has actually agreed to come by and help me out - he has much more experience than me.
He said it’s easier to use a battery powered hand drill, since there’s more control. But from the advice above, seems like a power drill might do the job quicker and better?
A battery hand drill is fine. Using a corded drill to put a guide hole in is overkill.
It’ll take a couple of seconds to drill those holes. And anyway, what’s the worst that can happen? You put an unwanted hole in the bottom of a desk. No one will see it and you will have learned from the experience.
Honestly, drilling small pilot holes is just about the smallest job one can give to a drill, any functional tool with “drill” written on it can handle this. The most difficult part of this will be marking the location of the holes, you will appreciate a second set of hands for that.
Mark the holes, use the correctly sized bit marked with tape to the correct depth. Make sure the bit is tight in the drill. Let the drill do the work, don’t push too hard or fast. You will be surprised how easy it is.
[QUOTE=teddybound]
He said it’s easier to use a battery powered hand drill, since there’s more control. But from the advice above, seems like a power drill might do the job quicker and better?
[/QUOTE]
A battery-powered drill is a power drill. My 18 volt drill has more torque than my old plug-in drill, and its ability to start slowly is where the more control part happens.
You shouldn’t need to drill. The ‘instructions’ indicate that you will need to drill if you have a hollow desk. If the desk is solid, then you can screw directly to the bottom.
The difference is the plugs/anchors. If the desk is hollow then it has a thin veneer wood on each side separated by corrugated cardboard or foam. You need the anchor to ensure you have the necessary support. If the desk is solid wood then the screws have enough material to hold on to.
Page 3 of the instructions show the 2 different methods, but are not clear what the distinction is.
If your desktop is solid just use the screws, but make sure the screw is shorter than the depth of the desktop.