Actually, if you look at the Apache config file then you have answer right there before your very eyes.
You need to make an alias, just look how Apache handles /icons directory and add your own according to example:
--- 8< -----------------------
<IfModule mod_alias.c>
Apache default alias for icons
Alias /icons/ "C:/apache/icons/"
<Directory "C:/apache/icons">
Options Indexes MultiViews
AllowOverride None
Order allow,deny
Allow from all
</Directory>
Your alias below where "/phpimages" is the
name by which it is later accessed counting
Alias /phpimages/ "c:/temp/php/images/"
<Directory "c:/temp/php/images/">
Options Indexes MultiViews
AllowOverride None
Order allow,deny
Allow from all
</Directory>
</IfModule>
--- >8 -----------------------
Just don't forget to turn on/off options you might need or not need (like turning off Indexes).