This little snippet was taken from zOWBscript, thought that maybe somebody might find it useful.

What does it do?
It detects if moo.mrc (sysinfo script) was found, and loads that if plugin loading is enabled.

Why/where would I want to use this?
If you're developing a script (such as zOWBscript) that also does sysinfo, you might want to give your users the choice between your sysinfo, and another sysinfo script (such as moo.mrc, in this case). also useful if you're an idiot like me who puts a half-working sysinfo script in his script ;_)

You can easily modify it to detect other (sysinfo) scripts with it. If you don't know how, you might want to dive into the mIRC manual and other various script-help resources. if you then still don't know, you probably shouldn't be scripting in the first place ;_)

Variables
(lines marked with a * are zOWBscript specific, you can remove them if you like, but be sure that all brackets still match when you do).

%z.sys.moo - availablity status, returns 'Available' when found, 'Unavailable' if not found.
%z.load.plugns - whether or not to load plugins
%z.sys.moo.loaded - loaded status, returns either 'loaded', 'not loaded' or 'failed to load'.
%z.set.sysinfo.moo - whether or not to use moo.mrc as sysinfo replacement

%z.pr - Line prefix
%z.col.hi - text hilight colour
%z.col.txt - text colour *

Notes
you might want to remove the comments before using, for some reason it parses the comments as something that has to be /set on a variable... no idea why.

      if ($exists(scripts\moo.mrc) == $true) {           ;if moo.mrc exists...
         /set %z.sys.moo Available                       ;...set it as available.
         if ($script(moo.mrc) == $null) {                ;if it's not loaded...
            if (%z.load.plugins == 1) {                  ;...and plugin loading is enabled...
               .load -rs scripts\moo.mrc                 ;...try to load it...
               if ($script moo.mrc) == $null) {          ;...if it's still not loaded...
                  /set %z.sys.moo.loaded failed to load  ;...set status to 'failed to load'
               }
               else {                                    ;if it was loaded successfully...
                  /set %z.set.sysinfo.moo 1              ;...make moo.mrc do the sysinfo...
                  /set %z.sys.moo.loaded loaded          ;...and make moo.mrc show up as loaded.
               }
            }
            else {                                       ;if we don't want to load plugins at start..
               /set %z.set.sysinfo.moo 0                 ;...do not use moo.mrc for sysinfo...
               /set %z.sys.moo.loaded not loaded         ;...and make it show up as 'not loaded'.
            }
         }
         else {
            /set %z.set.sysinfo.moo 1                    ;if the script is already loaded...
            /set %z.sys.moo.loaded loaded                ;...make it show up as such.
         }
      }
      else {
         /set %z.sys.moo Unavailable                     ;if moo.mrc doesn't exist...
         /set %z.set.sysinfo.moo 0                       ;...disable moo.mrc sysinfo...
         /set %z.sys.moo.loaded not loaded               ;...set it as 'not loaded'...
         /set %z.sys.moo Unavailable                     ;...and as 'unavailable'.
      }
      /echo %z.pr %z.col.hi $+ moo.mrc %z.col.txt $+ is %z.col.hi $+ %z.sys.moo $+ %z.col.txt $+ , %z.sys.moo.loaded
                                                         ; the line above this shows status, if it's available and/or loaded.