How to get an older emacs on Jessie

[Bob Bernstein <poobah@ruptured-duck.com>]

I have a need for an emacs older -- in terms of major version 
number -- than the ver. 24.4.1 currently onboard my i686 Jessie 
system. I suspect anything of ver. 23.n.n vintage would suit my 
purpose, which is to avoid ver 24's fussiness about older elisp 
code in a -- non-Debian -- package I am not willing to toss into 
the dustbin at this juncture, to wit psgmlx. Yes, I have brought 
this issue to the attention of the debian-doc list.

I *seem* to recall Debian maintained an impressive bunch of 
older emacs debs. I found one such version in the oldstable 
distribution, but I am loath to point my apt sources list at two 
distinct distributions.

Here's my current sources.list:

+++

deb http://debian.csail.mit.edu/debian/ jessie main contrib 
non-free
deb-src http://debian.csail.mit.edu/debian/ jessie main contrib 
non-free

deb http://security.debian.org/ jessie/updates main
deb-src http://security.debian.org/ jessie/updates main

deb http://debian.csail.mit.edu/debian/ jessie-updates main
deb-src http://debian.csail.mit.edu/debian/ jessie-updates main

+++

Can this be adjusted to allow me to install via apt-get this 
package?:

https://packages.debian.org/wheezy/emacs23

My fear is that if I monkey with sources.list I will trigger an 
unwanted dist-upgrade.

Best regards,

--
A person of great honour in Ireland (who was pleased to
stoop so low as to look into my mind) used to tell me that
my mind was like a conjured spirit, that would do mischief
if I did not give it employment.
                                        Jonathan Swift