1950 convertible door glass

[vilanar]

Hi,all.
Can you educate me... what is the procedure to install new door glass in the stainless frame of the convertible door.
I have the new rubbers but it seems to be impossible to slide the glass in place because there is those spot welded tabs which are inside the frame.
I used the search function , no luck and google wasn't my friend this time....
Any help would be appreciated.

Ari