I got it sorted out!
Ktsuss is great for the multiple-DE scripts! Though it crashed when I tried the command ktsuss -?
Also, it appear that kdesu can be used, it just need the parameter -c before the command - I guess kdesu has changed this a couple of months ago, it worked before without -c
Using sudo require the username in sudoers I guess - haven't double-checked.
Again, thanks for all the answers,