This depends on the Routine, if you got it from the Buddystore and it get's streamed to you, there is no way you can edit it.
But if it's a opensourced routine in your /Routine folder, you can modify it there.
If the combat routine comes in a .dll file most likely there are also some code obfusciating measures to make sure you don't easily get acces to the source.
Since if this is a paid routine we are talking about, if anybody could easily see and change the sourcecode, they could just sell the routine themselves.
best approach would be contacting the author about your changes, maybe he's willing to implement them himself