In thinking about it, I’m sure you could come up with a way to merge a file with your timing information into your acqknowledge datastream, but it would be a major pain, and needlessly challenging.
I would imagine that one way you could do it (and I would not recommend doing it) would be to save your acknowledge data as a Matlab file. Then open the data in Matlab–it will be a datafile with different columns for your different biopac channels. However, the data will be in the file at your sampling rate. So for instance, if you have recorded at 250 Hz with Biopac, then you will have one datapoint for every 4 ms (assuming my brain is working at the moment) for every biopac channel (these are large files). So to accurately merge in your timing signal, you’d have to get the data from Superlab in a format that would let you figure out where in the datastream you would insert a new timing signal variable, and you’d need to format the data in Matlab correctly. Again, you would have some uncertainty about whether Superlab and Biopac were perfectly in synch across the recording, given that they were not linked up (they probably wouldn’t be hugely off, but again, there will likely be some noise there–and the extent of the problem depends upon the nature of the data you’re recording and how much temporal precision you need for your analysis).
Again, though, even if you could do it, it would be a giant headache and the results would be questionable. I’d really recommend taking the easier (although slightly more expensive) route of buying the hardware to synch your superlab presentation computer with your acqknowledge recording computer.