I think what RBJ is suggesting needs a lot of experience - an ear for the absolutely right and perfect tone - as simply 'making' the tones sound like sa, re, ga, ma... can be misleading cuz even if you get all your tones to sound right in order together, what if the first itself is not the right tone? I suppose you get what I mean.
A better way is to use to use a synthesiser to help you tune your guitar. Alternatively, google for 'guitar tuner' and several websites will popup that carry simple midi-based tuners from where you can tune just as if from a synth. I've attached below one such simple tuner from http://www.hotfrets.com/tuner.asp.
The best way is to use a digital tuner like the simple and dedicated AP Guitar Tuner (http://www.cerlsoundgroup.org/cgi-bin/aptuner/ftp/apmain/APTunerInstall207.exe) or the advanced and multi-featured GuitarFX Box (http://www.guitar-fxbox.com/fxbox26.zip).
It helps if your's is an electric guitar or an acoustic with a soundhole pickup, else you'll need the computer microphone to tune using the above digital tuning softwares.
Many times I've lied, many times I've listened
Many times I've wondered how much there is to know...
Mellow is the man who knows what he's been missing
Many many men can't see the open road...
Many is a word that only leaves you guessing
Guessing 'bout a thing you really ought to know...