Converting .png to .icns through Terminal

Hi all,
I'm a newbie to MacOS and I've been trying to use unix commands at the terminal to convert a custom made icon from .png to .icns.
I've tried:
sips -s format icns [png file] --out [(converted file).icns]
apparently sips doesnt recognize icns! so next I tried:

Converting a .png to .tiff and then .tiff to .icns
sips -s format tiff [png file] --out [(converted file).tiff]
tiff2icns -noLarge [tiff file] [icns file]
Result was an utter disaster. the convert was successful but the quality was pathetic.
I havent thoroughly researched the net. But the whole ordeal is getting frustrating. Can some one help?

I have never tried this but look into Automator to make this switch. I have read it does batch conversion so try that. Wish I could guide you but never been there.

Thanks! I tried Automator... it sure works.. but the quality is compromised... Any suggestions?

Do you have to do this via the command line? You might wish to try out the excellent freeware Iconverter:

http://www.students.niu.edu/~z110241/index.html

I use it regularly and it is quite good. Very plain and simple interface, but very effective at what it does.