The way I was taught to do it was to add a little bit of the hot liquid to the eggs, then add the egg mixture into the hot mixture. Usually about a quarter cup of hot mixture is what I use.
Yep, that's it.. it's called tempering.
The best way, Bonnie, is to use a double-boiler. Do you have one? If not, can you jury-rig a bowl which fits over the rim of any of your pots?
Put some water in the pot, fit the bowl on top, heat the water to boiling and reduce heat to medium-low (keep the water at a gentle boil). Pour your filling or custard or whatever into the bowl. Add the eggs. Stir constantly until quite thick. The eggs will of course cook (you want them to be cooked). But you won't have to worry about clumping and lumping and poor consistancy.