The first developer time will be whatever you find it to be. Start with standard dilution for 6.5 minutes at 100 degrees. If the slides are too dark increase the time of the first developer. The second should go to completion so it won't matter as long as it's all getting done.

Remember that these slides are not going to be optimal without the proper developer. They will probably fade and have weird dmax and color shifts.

Rhodes: The normal E6 process includes a chemical that fogs the film for you. Since you don't have it, you'll have to re expose to light. Any light will do. Just use enough and not too much. Simple, right?