Thank you very much for the explanations guys (it was a very good explanation bu JMI). I tried to reply earlier, but I think an anti-spam system prevented me (It said I couldn't post again for 24hours).

taos - thanks for the tip with "getting OEP", I was previously googling for "unpacking aspack" and didn't make any ground with the tutorials I found, but adding OEP led to a nice tutorial here here.

ne_viens, I dont want to just unpack the file - as then I have to give my friends the complete file, rather then just a little patch. Thank you for the example code!

I have now finished the patch and all is working well, so im very happy.