You can still access haxchi as a channel on your home menu if you want? usually after installing cbhc your haxchi channel will keep the last install so if you install cbhc at first, it should keep as your original homebrew haxchi method ds title on your cfw system menu, if you install cbhc again, it will have a cbhc menu come up not straight to homebrew launcher as it did, not your last haxchi homebrew channel settings, if you understand me that is I know it sounds confussing! If your getting a black screen entering haxchi again, which you shouldn't really are you sure your not using the version of homebrew launcher for .rpx and not .elf version because this is a known issue? Tbh if I was you go and install cbhc again> go back into your homebrew launcher in system menu cfw and run cbhc install, when you go back into your cfw system menu and start up your haxchi DS title it should have a separate cbhc menu like it does on boot up, that you can use completely separate than your real cbhc install, its quite handy. Apart from than that, like
@Kafluke mentioned just install channels on your cfw system menu using gx2 wupinstaller. I'm sure this is what it did with me but tbh I was running my own custom code coldboothax menu so I was constantly testing it out but I'm sure my original haxchi title kept the last install every time I installed cbhc again, it would go like 1>2 then 2>3 and so on, on the cfw menu. Mind you I did it so many times such a long time ago I'm probably completely wrong and just lost touch now but I'm 96% sure that's how the install goes!