How to put other country maps (India in my case) for FREE on a Garmin nuvi 40LM GPS that was purchased in USA

I purchased a Garmin nuvi 40LM GPS in the United States. It worked beautifully well - so well that I did not want to part with it when I was moving back to India. But the challenge was not how to put Indian maps on it (that you could purchase online any day) - but the challenge was to put them for FREE!
Now since I was going with the free option, I knew I would have to compromise on a few things and I was completely ok with that. So this technique is not for those who could shell out somewhere around ₹5000 for maps that work great and save on a few hassles. I personally felt that in India you really don't need GPS that much, you could ask anyone anywhere on the road and they would be able to guide you to the best of their knowledge. But this technique is for those who just want free Indian (or any other country) maps and can compromise on a few things (which I'll explain later).
Let's start with the process!

Getting free maps
There's a great site to get free maps for Garmin devices: http://garmin.openstreetmap.nl/
I selected the following options:

1. Map type: Generic routable (new style)
2. TYP file: No
3. Country: India
4. Additional tiles: No

Then click download. It would take you to a page where you'd need to download the item you want. Since I was using a Windows PC and I had BaseCamp installed, I selected the Windows exe option and downloaded and installed the file.

Wiping out existing data on the GPS

This step is optional/on-need basis. I did not have an extra microSD card with me so I wanted to wipe out my US maps and favorites from the GPS internal memory to clear up space. I followed this procedure but it did not delete my favorites somehow so I manually deleted all of them. I also manually deleted all the *.gpx files from the GPX folder in the GPS (you can see this folder once you connect your GPS via USB cable to your PC). Deleting these gpx files was needed since my GPS threw up a "Cannot calculate route" message otherwise when told to Go to a certain address.

Using BaseCamp

BaseCamp is a Garmin software which you can download from here. We would need this software to put our Indian map on the Garmin GPS (and also delete the existing US map from there). Once you open BaseCamp and you have your Garmin GPS connected via USB, you would be able to see your GPS device's Internal Storage on the left hand side in BaseCamp.

1. Right click on Internal Storage and select Install Maps.
2. Once it finds your GPS connected to your PC, you can click Continue.
3. Now you should deselect the map(s) you do not want (US in this case) and select the map(s) you want (India in this case). This screen also displays the available and required space at the bottom. You can also use the Advanced/Partial Install if you are running out of space.
4. Hit Continue and the maps would be sent to your GPS device!

THE compromise

Since these maps are open/free, they rely on being constantly updated by people like us. They do not have a full fledged database ready to be used, so, they do not contain all the cities/streets/addresses in India. But their tiles do cover the whole of India - which means if you do not find a street/address, you should make use of another important feature of your GPS - Coordinates! So for example, if I need to go to a place my GPS cannot find, I look for the latitude and longitude of the place in my phone (I use GMaps app, you can use bing maps too. Google maps unfortunately does not provide coordinates on phone). GMaps provides coordinates in degree, minutes and seconds format; bing provides them in decimal degree format. I convert them into degrees and decimal minutes format which my GPS undertands and then hit Go! It takes me to that place beautifully!

Hope this helps!