You don't have to throw the old configuration out at all.
Assuming you put the game in "lolcd" under "oldgames":
mount d: "c:\users\andy\oldgames\lolcd\cd\" -t cdrom -label LOL_CD
mount c: "c:\users\andy\oldgames\lolcd\"
#mount c "c:\users\andy\oldgames"
#mount d "e:\" -t cdrom
c:
Adding a # mark at the beginning of a line in the config file turns it into a comment - DOSBox will not execute it unless you remove the #.