iDVD doesn't support external burners! a while ago, there was a patch/hack for 10.1. form a compp OtherWorldComputing to override that, but it was pulled by Apple…-
the brandnew iDVD4, part of iLife 04, offers the possibilty to create images for use with other computers…- no idea, wether you can burn these images with toast (i do use it - very good prg!)… if you live in the US, go to the next Apple Store, ask the geniuses…-
no, if you want to use iDVD, you have to connect the burner directly to the internal IDE bus (i did that with my Cube - some very hard modding: you have to cut holes into the buttom of the Cube!!! … never try this with such a design masterpiece

)