I think you can change the oom priority to a negative
dialer is -12
android system is -16
launcher is -12
messaging is 0
most apps are at a 4
-17 is the oom limit. OOM is an app killer set by android to help it automatically shut down apps..
Auto memory manager lets you set it also.
I found a write up on the process at
xda-developers - View Single Post - How to configure Android's *internal* taskkiller
Otherwise your looking at doing some code mod's
services/java/com/android/server/am/ActivityManagerService.java.......
I also saw some people using task killers with a keep alive option.
not great ideas but something..