Catlover, this poster states her location is Mumbai. There are squat toilets there. Though there are toilet pots like we have too, I believe this poster is referring to a squat toilet. Teaching a lab to squat over a single specific location, which is basically a hole in the ground, would be a LOT easier than the image you've got in mind. However, I have not seen it or heard of it, though I am sure that it has been done. It might be a bit finickier to get the dog to poo in one specific spot, or to get it to urinate while squatting.
You could put the dog on a strict routine. The routine will help you learn when he needs to eliminate, and it helps him find confidence more quickly rather than having a guessing game about when he might need to go. Ten to twenty minutes after each meal or drink or waking up from a nap (it depends on the dog how long that time will be; see first what time works on average for Romeo so that you have a better success rate for the following), take the dog to the toilet, and tell it "go pee". Do not leave that area until the dog has gone pee. The closer the dog is to the toilet, the bigger the treat or praise. Say "good pee" immediately after it has finished peeing, with a treat or with praise in whichever way you tell your dog it's a command or job well done. You say you have drops; I assume those are drops that encourage a dog to use a specific location for going pee. If those are in the toilet, it might be very quick to teach him that.
Now while you are doing this training, whenever your dog goes poo (doesn't matter where), give it another word. For instance, "Go poo", or "get busy". Get Romeo to associate that word with going poo. Make sure it is a word that is not a common phrase so that he will not get confused if he hears the phrase when he shouldn't be going poo.
First say it when you see he is squatting to go poo. Then say it when you see he is preparing to go poo. When he is finished, say good poo, or good busy, and combine that with a favourite treat or form of praise. You'll have an idea of his poo schedule based on his meal times... so after you've established when he needs to go, and that he understands the word for poo, take him to the toilet, and point at the toilet and say the command. Do not allow him to leave or be distracted. Do not play with him or talk with him or pamper him... he's expected to do a poo, and after the poo there can be love and fun and treats again.
I hope that this helps you on the path to training him. There are other options, such as "clicker training", where you use a little object that makes a clicking sound to mark a location or behaviour that you wish to encourage. Here is a link to further information about it:
http://www.clickertraining.com/what_is_clicker_training