7401's are an interesting proposition for straps. I've set up a couple of our riders who wanted to use these simply because they had them around and didn't want to spend extra on their first track bikes. We came up with three solutions:
First, and easiest, is that a toe strap simply loops around the back half of the pedal (just behind the axle) and actually stays in place very nicely once tightened without anything else needed. There are really only two places on these pedals where the strap wants to end up (because of the shape of the underside and sides of the pedal) -- right behind the axle and completely behind the pedal. The behind-the-axle version actually works pretty well for most people because the behind-the-pedal version is farther back than, say, on SPD-R's. Now there is an allen bolt on the underside that seems to come out and go back in without blowing up everything inside (I've done it once), but I've learned from bitter experience that until you've done it a bunch of times on a pedal, you don't know for sure that some pedals don't want to explosively deconstruct when you do this. If you are willing to experiment, absolutely go for it.
Second, you can disassemble the quick release mechanism and put a bolt with a wingnut (or an allen head cap bolt, if you don't mind tightening your cleats with an allen key screwdriver) coming out a hole drilled in the back plate of the pedal and running to the spring flange about a centimeter forward of the back plate. It simply clamps the pedal quick release clip on the rear into your cleats, and they're locked in until you loosen the allen bolt. There is no clip-out, which makes them quite secure. As I suggested in the SPD-R thread, if you're using a velcro-strap shoe like a Poggio, you can just leave the shoes on the pedal and slip in and out of the shoes. Then you can also add a strap (just wrapped around the pedal and shoe, no fastener to the pedal) and not have to worry about it if you want that extra comfort or think you're going to rip off your shoe's uppers.
Third, you have plenty of aluminum in the body of the pedal to tap a hole for a clip mounting. But I'd actually suggest sanding off a small area on the bottom of the pedal and using JBWeld to bond the loop from a toe clip directly onto the metal of the pedal. So far this hasn't created a problem, and you can customize your strap positioning. This is simple and dumb, but seems to work as well as drilling and tapping holes.