Most of the current techniques proposed are extremely low-bandwidth, mainly focused on pre-digital age techniques. It makes more sense that a starfaring alien race would be far more advanced than humans, and they should be able to do far more with digital techniques than we can.
Even if the mind onboard the nanobot is of human intelligence, the nanobot itself should be equipped with powerful digital manipulators capable of sending signals either via wired or wireless connections, allowing the mind to make digital connections.
Wi-Fi and radio
I would disagree with the author's claim that a nanobot the size of a mosquito doesn't have enough space/power to implement a wireless radio.
Micron-sized graphene nano-radios (2-4µm in diameter) have been built with existing human technology with sufficient quality to transmit FM radio audio signals. It is clear that alien nanotechnology which can power a complete sentient mind within a structure the size of a mosquito can do much better in terms of miniaturisation.
On the power side, radios require very low powers to operate. The S-scale used in radios measures the received signal intensities, and signals below -100dBm can be detected. This translates to powers of 0.1pW. For comparison, the kinetic energy of a flying mosquito is about 160 nJ, which is three orders more energy than it takes to transmit at -100dBm for a second.
Therefore, the mosquito-nanobot can simply announce its presence on the nearest FM or AM radio by directly transmitting an audio signal into the antenna, which would be picked up and amplified as audio signals.
Alternatively, it can also hijack the nearest WiFi access point by flashing its firmware. 790
Many access points have weak (WEP) or no protection, allowing them to be hacked and used for information dissemination by the mosquito nanobot. USB
In any case, the usage of a radio is completely unnecessary, when you can essentially perform arbitrary actions on a target computer.
USB is a convenient mechanism that allows arbitrary devices to be powered directly from the port and which often trigger autorun programs on the attached computer. USB can also be used to drive keyboards and mice, which can be used to display programs in plaintext on the targeted device.
For example, the mosquito-nanobot can connect to the USB port and masquerade as a USB keyboard. On a Windows machine, it can then enter the key sequence Win-R , notepad , enter followed by arbitrary input announcing its presence. Even if the nanobot did not already know the USB keyboard protocol, it could easily tap the signal of an actual keyboard and quickly learn the correct sequence of electrical signals required for sending keystrokes to the computer. A plot point can be made on the alien making incorrect keystrokes during this learning process, causing the human protagonist to suspect that his computer has been hacked.
It can also announce itself as a USB hub, which has a mass storage device as well as a keyboard attached. It can then load arbitrary images, text, audio and video onto the computer of the target in order to convince the target of its authenticity.
Mass media studios
While televisions are on the way out as a form of mass media, many people still watch television, especially so for the case of news broadcasts, which are often live and therefore not subject to editing, allowing the alien nanobot to inject audio signals.
The mosquito nanobot could position itself on the line-in connection of a microphone wire, and transmit audio signals that are broadcast to the entire audience of the TV station.
This has the added benefit of causing a number of alien fanatics to become primed towards the existence of the mosquito alien, which would make its job much easier at finding receptive people for it to converse with and who will believe the messages. 790