Well that was the first problem... it is impossible to have a ctf mode with an endless round, even if everyone is eliminated (apart from server side options). In koth, when everyone is elimnated the round doesn't end. This would be perfect, however the two teams can't have hills specific to their colour, so then I tryed gamemode 20 (ctf+koth) I couldn't get that to work either. I might be able to send you the bsp and map files tommorow to help you understand it more.
Basically:
You spawn, the objective is to run to the enemy base and score a point by standing on a point in their base, once you stand on that point you simultaneously gain a point for your team but you are also killed by a trigger hurt, sending you back to your base.
How I made the point scoring position in the enemy base:
-CTF method: Made a hole. You fall into the hole to score the point. In the hole there is a flag (team 1) and a base (team 1) so you score instantly. At the bottom of the pit there is a trig hurt to teleport you back to your own base, however I don't want this to end the round, that is how this method is flawed.
-KOTH method: Made a hole. You fall into the hole to score a point. In the hole there is a hill and a trigger hurt of 2, allowing enough time to score 1 point. However, this method is flawed because there must be a capture point for each team and koth only supports one hill for both teams, not a hill for one team and a hill for the other.
I tried gamemode 20 but i don't really know how that works and it didnt work. It is important, that there is no round ending, that you score by standing on a point at the enemy base, and that you get teleported back to your base once you score.