Freeshards usually require people to download the shard you play on to give an answer, posting the freeshard you play on may get you more help than a vague description of how it works. I don't know much about stealth other than it works similar to euo. Your going to have to write it, its not as hard as it looks.
X * Y + skill = Z
#str * %howmuchskillper + #skill (identify the skill first!) = %totalskill
There is a wiki to help with math in scripts and it should outline everything you need to do it.
Otherwise you would have to write it to identify the numbers on the skill chart and that would be several thousand times harder as it has to do with pixels.
There is a write up by cheffe on how to do this, I dont know if we are allowed to post links to other forums or not, so your going to have to search for it. but i suggest not attempting that as it seems to be an advanced scripters only.