Ummm...to your answer about modifying, no.
But, I believe we pretty much offer the option you want already.
Ok, though I KNOW we Ulysses team members LOVE XGUI for making so much so simple, there are times it just doesn't show all the information that our actual config files do.
From ULX's gmod/data/ulx/config.txt, regarding reserved slots.
ulx rslotsMode 0
ulx rslots 2
ulx rslotsVisible 1 ; When this is 0, sv_visiblemaxplayers will be set to maxplayers - slots_currently_reserved
;Modes:
;0 - Off
;1 - Keep # of slots reserved for admins, admins fill slots.
;2 - Keep # of slots reserved for admins, admins don't fill slots, they'll be freed when a player leaves.
;3 - Always keep 1 slot open for admins, kick the user with the shortest connection time if an admin joins.
;Difference between 1 and 2:
;I realize it's a bit confusing, so here's an example.
;On mode 1--
; You have maxplayers set to 10, rslots set to 2, and there are currently 8 non-admins connected.
; If a non-admin tries to join, they'll be kicked to keep the reserved slots open. Two admins join
; and fill the two reserved slots. When non-admins leave, the two admins will still be filling the
; two reserved slots, so another regular player can join and fill the server up again without being
; kicked by the slots system
;On mode 2--
; Same setup as mode 1, you have the two admins in the server and the server is full. Now, when a
; non-admin leaves the server, reserved slots will pick up the slot again as reserved. If a regular
; player tries to join and fill the server again, even though there are two admins connected, it will
; kick the regular player to keep the slot open
;So, the basic difference between these two is mode 1 will subtract currently connected admins from the slot
;pool, while mode 2 while always be attempting to reclaim slots if it doesn't currently have enough when
;players leave no matter how many admins are connected.
;rslotsVisible:
; If you set this variable to 0, ULX will automatically change sv_visiblemaxplayers for you so that if
; there are no regular player slots available in your server, it will appear that the server is full.
; The major downside to this is that admins can't connect to the server using the "find server" dialog
; when it appears full. Instead, they have to go to console and use the command "connect <ip>".
; NOTE THIS DOES NOT CHANGE YOUR MAXPLAYERS VARIABLE, ONLY HOW MANY MAXPLAYERS IT _LOOKS_ LIKE YOUR
; SERVER HAS. YOU CAN NEVER, EVER HAVE MORE PLAYERS IN YOUR SERVER THAN THE MAXPLAYERS VARIABLE.
And, I forget the name of the permission, but if you look through the permissions for your admins, find rslots or reservedslots or something similiar, and add it to your donator group.
(All the above options can be modified using XGUI....XGUI just doesn't explain them quite as well)
