Check out the pos function. For example:

$str = "aaabcabcdebcaabebcb";
while($str =~ /(\w{3}bc\w{2})/g){
    print "$-[1],$+[1],$1\n";
    pos($str) = $-[1]+1;
}
[download]

This sets the position to start looking for the next match to 1 past the start point of the previous match. And it gets you the output you want.