Pour one tin (300 g) into a bowl. Add the coffee liqueur, a third cup at a time into the bowl and mix well.
In a separate bowl, add the remaining 3 tins of cream; whip in the coffee cream a little before adding the sugar and salt. Combine ingredients and stir until sugar is dissolved.
Pour into hand or electric freezer can and follow manufacturers instructions.
Here are recommended steps for the freezer method......
Chill the ice cream mixture in an ice bath.
Pour mixture in a bowl (plastic, stainless steel) and freeze.
Check after 45 mins...When it starts to freeze around the edges whisk it vigourously and place back in freezer.
Check every 30 mins and whisk vigourously every time.
Continue checking the ice cream, stirring every time while the ice cream freezes.