I've loved this GCBOS ever since I saw it on a forum I modded a few years back, and I've always used this on my vB4 forums.
Both yes and no. Yes, if you edit it. No, if you just install it as is.

If you install it now, it WILL give you the error "Call-time-pass-by-reference has been removed from line 125 in public_html/root_folder/includes/class_gcbos.php"

However there's an easy quickfix for this.
Go into line 125 in class_gcbos.php. It'll say
All you need to do is find "&$output" and remove "&" from it. Then it'll look like this;

Which works fine on my forum.
Hope this helps!

---Edit---

Now you might encounter "Function split() is deprecated in gcbos.php on line 109"

Another quickfix is available for this. Go into gcbos.php on that line, and replace "split" with "explode".
/help doesn't work, but everything else should work fine. (Note, I haven't tried all the commands yet, but I assume that they work as /me, /prune and /notice works)