Software Deployment

I was wondring if it always works to add an isscript.mst to an installshield package?
I have read some posts here on the subject but so far i havent figured it out yet or got it work
The post i have been looking at is

http://itninja.com/question/msi-corporate-standardiser6&mpage=1䶊

I got the package to work by adding to the mst the properties ISSETUPDRIVEN=1 and deleting OnCheckSilentInstall custom action from the InstallExecuteSequence table.
This situation depends on that i install the isscript.msi first

But if its possible to only use the main package and an mst which contains the isscript merge module i would preferable do that

I tried doing the the method that AngelD wrote in his post. But somehow it did not work
It give me a message that the isscript engine is missing from this machine.

This is what i did
1. Opened the isscript9.msi in wps 7 sp2 and generated the merge module( Here i got a bunch of dll's and and msm file)
2. Opened the orginal msi file in orca? Do i have to use orca by the way? Choose new transform. Added the msm from the installshield.msi like AngelD wrote on the subject. Got some conflict error but simply clicked ok
2. Added the properties ISSETUPDRIVEN=1 and deleting OnCheckSilentInstall custom action from the InstallExecuteSequence table.
3. Saved the mst

Then i tried to install it i got the error message above

So
1.Could it be that i have done something wrong in creating the merge module?
2. Does this procedure works for all installshield packages?? If not how can i figure out which packages it will work on etc.

Hope someone here could help me out