Hi Seriousperson
Looks to me like you have 2 possible options
Use ECL as a substrate for HRP, commonly used for detection in western blotting applications, for example
Or, you could go for a different secondary, say alkaline phosphatases, a variet of detection substrates are available using this system, so you could try this, just google "alkaline phosphate substrates" and see what you get
Hope this helps you out, cakeman