Need advice for upgrading (21.3 --> 21.4)

[Madhusudan Singh]

Hi

 I am using emacs 21.3 (I compiled it myself with elisp, leim, auctex,
dvipng, etc.) on Debian Linux (Sarge).

 I wish to upgrade to version 21.4 from sources. My emacs installation is
located in /usr/local/emacs. What is the best way to upgrade from source
while making sure that none of the configurations and the great packages
that I have installed after a year or so of use, get lost, and work with
version 21.4 ?

Thanks.