That depends on what type of installer the patch uses. Some installers have had programs written specifically to extract the contents like:
I5COMP & I6COMP for Installshield
INNOUNP 0.15 for Inno Setup
WUN 0.90A for Wise Installer
Installshield and Inno Setup are probably the only 2 installers you could add files too, Inno would need to be recompiled using the script extracted using Innounp.
Belive me, it's more trouble than it's worth! Ask Grumpy
