Yes, I believe you can use only 1 can light with the controller and then seek other controllers for other lights.
Honestly I'm not sure about hooking a manual trigger into it. I do know that it has a mic port on it. Below is what the website states:
Elation T4 Four-Channel Chase Controller Features:
One- to ten-minute timed chase
Instant sound-to-light chase
Four standard three-prong plugs
Timed, audio, or chase modes switch
LED channel indicators
Hanging bracket for easy mounting on light stands
The Elation T4 4-Channel Chase Controller allows you to coordinate your lights and your music for greater impact. 4 standard 3-prong plugs. The chase light controller has timed, audio, or chase modes switch and speed knob. Built-in mic and LED channel indicators. Hanging bracket allows easy mounting on light stands.
Based what I have seen from it I don't believe you can do a "plug and play" on introducing an external manual control. I will say that it is possible to wire in a manual control to the T4 controller if a person knows what wire to splice and solder in a manual push button or something to that effect. However doing so may introduce other variables that may not be wanted.
(Assuming this is what you are asking about.)
Don't forget that most of the LED stage lights are coming down in price and are EXTREMELY more effective than the traditional halogen lighting. Yes it's more up front cost, but you save in bulb replacement, electricity bills, and the LED's are capable of changing colors so fewer halogen lighting as well as not as much heat in the haunt. They truely are a great asset.
In my experience if you are wanting to have a device, such as a strobe light go off when the audio has a thunder clap, a mic such as the one the T4 has is the best way. If you want a system designed to sequence lights with an audio track than I suggest a programmable lighting controller board. You will spend a little more but the results will be VERY professional.
I know when I worked with Rocky Point Haunted House in Salt Lake City, Par 68 can lights were used on a track where they had dancers entertain patrons waiting admittance into the haunt. The lighting was programmed with something like what's above.
IMO if you want a professional haunt, don't skim on lighting. Professional lighting = professional experience.
Side note: I'm not trying to suggest guitar center is the only place I shop or where you can get such equipment; merely that they were the fastest reference at this time.
I hope this helps a bit. (Maybe too much info?)