Thumbs up [Q] Best way to keep app in memory?

Ok first of all hello everybody and welcome to the ultimate mythbusters thread about keeping apps in memory.

I would like you android pros, geeks, programmers, etc to answer me a simple question about android.
Answers may differ but i would like to solve this mystery once and for all:

How do i keep a d*mn app in my phones memory?

Little background sittuation, I want to "bulletproof" an application called hello sms and possibly other apps...
I would also love to know wich of these methods actually works:

1) add to build.prop

ro.sys.keep_app_1=com.hellotext.text / sys.keep_app_1= process here

2) init.d script (credits to zepplinrox, he is awsome and i saw this script on one of his threads)

#!/system/bin/sh
sleep 60
PPID=$(pidof process.here)
echo "-17" > /proc/$PPID/oom_adj

3) other init.d script (also credits to zpplinrox, but this one i got through digging on supercharger v6 rc 13 script..)

#!/system/bin/sh
sleep 60
PPID=$(pidof com.process.here)
echo "-17" > /proc/$PPID/oom_adj
echo "-1000" > /proc/$PPID/oom_score_adj
renice -20 $PPID


Whats the best way? I heard that the first one only works on 2.3 android, not on 4.0+, is that true?
Wich one of the init.d scripts works best? If one of them works how do i make it loop?

Dont tell me to use supercharger v6 bulletproof option because although it is a great script im trying to add all those tweaks
to my personal rom already in the instalation (no later tweaking, just flash it and bam, working)

Thanks in advance, and i hope someone can enlighten me and the whole xda forums