its difficult without the right tools like a signal meter. it can be done though. i did it successfully for my dish tv but botched up the alignment again while messing around with it trying to get a foreign channel.
First you need to know the satellite orbit of TSky. From various sources like lyngsat etc it (Insat 4A satellite from which tata sky is beamed down to us) is at the 83.1E geostationary orbit.
Then you need to know the latitude and longitude of your terrace/ place where your dish is fixed.
Use this -
India satellite dish pointing and aiming calculator
If you see properly on the map there is a dot a pixel in width and height which keeps flickering in center of the google maps window. that is the spot you need to center on your building. When you get the almost exact spot you will see the latitude and longitude below the map. It would be something like --deg N --min -- sec etc.
you should also use the (Optional) Pointing angles to satellite orbit longitude option. i used NSS6 there since i have dishtv. You will use 83E Insat 4A. And the blue line pointing to your location in the map is the line of sight from the Satellite to your dish.
You will get these values:
Dish elevation= something, Azimuth= something (magnetic compass), Polarisation= something
Polar mounts only: Main angle= something, Downward tilt= something, Motor drive sideways angle= something (---> these not for us)
use these values to fine tune your dish. ofcourse you'll need a magnetic compass to do that. The chinese make ones are available for 50 bucks or so in stationary shops.
If you need to know the signal strength or if signal is locked etc and do not want to run up and down from terrace to your flat, then you will need to have a small tv (if possible, so you can take it to the roof to see the signal strength) plus your tsky stb + power source (long extension wire). You also need a meter or two of the same type of cable which comes from the stb to the lnb.
just attach the stb to the lnb and switch on power. You should set your stb to settings menu where you can see the signal strength while making the adjustments to dish now.
After making all the adjustments finetune the lnb so that you get around 80-85% signal strength. you just need to move the lnb in up down direction by half a degree or so to fine tune it.
I tried this just for the heck of it one sunday. took an hour or so since i didnt even have a compass nor any of those satellite signal meters

ashamed). i just printed a protractor on an A4 size paper and had it near the dish while aligning it. worked well and my stb locked on to the signal. strength i got was around 75% on all transports. must have been pure luck
but its ok. its not rocket science and can be done. best of luck
Edit: You can also use this tool for aligning your dish. See the satellite offset page to get an idea of how to align the dish.
http://www.al-soft.com/saa/satinfo.shtml
install it carefully. there's some 3rd party tool wrapped in it which you can decline.