alright so... the EASY way is to go ahead and install it... (i'd close the website down on maintenance)
then open the failed files, and the packages .xml or .mod file that changes the code in files.
Find in the code the file name, and do a search for a simplified version of the code it searches for.. EX: if it says..
'value' => 'this is something',
search for 'value'
position makes a difference. If it says "position = before" that means the added stuff will be added AFTER that code. if after it means BEFORE and replace... stays the same.
if u need more help just ask...