Ok clearly the question is very specific, tht no one cared to answer. so if some one else wants to know how to add custom edit buttons in Mediawiki, this is how I did it
I found a Mediawiki help page which asks the user to edit a particular javascript page located at http://(wiki-site-url)/Mediawiki:Comomn.js
.
On closer inspection this is not an actual js page but a normal wikipage(stored in the database as wikitext) which is loaded by mediawiki during runtime. The site admin can edit this page by adding
if (mwCustomEditButtons) {
mwCustomEditButtons[mwCustomEditButtons.length] = {
"imageFile": "<path-to-image-on-the-server>",
"speedTip": "Comment visible only for editors",
"tagOpen": "open tag",
"tagClose": "closing tag",
"sampleText": "Insert comment here"}
}
This can also be achieved for a single user by applying the same edit on the users own copy of the js file available at http://(wiki-site-url/User:(Your_username)/(skinname).js
Both the js pages could be created if they dont already exist.