Two ways. If Toast dosn't open the file then use MacLink Plus.
1. Open toast ,open other, select disk image drag the dmg file onto Toast and select mount disk. If a disk dosn't show on your desk top go to.
2.Open MacLink Plus Drag the dmg file onto MacLink Plus, open the file icon and select the lower icon, select decompress on MacLink Plus. The file will open the same as expanding it with stuffit . When the file has expanded it will also be a dmg file, go back follow step 1. You should now have a disk image of the file on your desktop. Cheers
Timewaster