Simply edit the tooltype of the picasso monitor located in devs/monitor adding the resolution in this way :
MODE=640x480@60
MODE=800x600@60
and so on..
If your system still boot on aga, check that the flag " executable " is checked in picasso monitor or it won't work.. ( you said that you copied from cd ) sometimes even during the installation at the end an error about " protection " show up here on my miggy and the voodoo doesn't work for that reason..
maybe..
Edit: almost forgot, set also the Horizontal and Vertical frequencies of your monitor !