Unless you have an ISB engine you probably don't have a computer. The wiring of the grid heater is pretty straight forward. Install it on the intake plate (might need a new plate if yours doesn't accommodate one). There may be one or two relays that send the power to the unit. Those are wired directly to the battery (a fusible link is required). To trigger the relay assembly, use a momentary on or push button switch. Engage it for about 10 second or less and then start the engine. Remember those heaters use a lot of current so you don't want them on for a long time. Will quickly drain the battery. The units that had dual relays were designed so the vehicle computer would activate only one half of the grid in less cold weather. You can decide whether you want to tie the two sections together or use two switches on the dual relays. With the 4bt, you become the computer. An alternative to the grid heater is a device called a thermostart. It's a very simple device that uses diesel fuel to heat the intake chamber. Those are cheap and use far less battery power to operate. Those are very common on farm tractors. You have a small diesel tank ( probably less than a pint) that feeds the unit. They make tanks that can be plumbed into the return line so it's always full. When the power is applied, the unit heats up and a valve opens letting diesel drip on a hot coil. The fuel ignites and you have a fire in the intake. Instant heat.
