NASA has funded SBIR topics on automating EVA scheduling; TRACLabs (based in Clear Lake) has done some of this work, see http://traclabs.com/research/our-thought-leaders/ and particularly work by Debra Schreckenghost, Pete Bonasso, and Scott Bell.
So NASA is developing automated scheduling tools and prototypes exist, they're just taking some time to reach your desk.
I've met Pete. Unfortunately their solutions don't handle the parallel nature of what we're doing. They have essentially written an Eclipse plug-in if I recall correctly.
They were using Eclipse as an interface for task creation and presentation; there's AI in the background ordering the tasks according to, eg, minimal procedure time. While their website is a little sparse, I think an email would prove useful.
Also, as I understand it, you're asking for solutions to the wrong problem. While any sort of project planner would be an improvement over scheduling in Word, the reason you don't use that already is a certain rigidity in how EVAs are planned. If that rigidity were overcome, you'd be able to use a simple project planner, and you'd also be able to use a much more advanced solution that ensures that no tasks collide.
