Sorry for the delay. The topic reply notification must have been in another part of the world to have taken so long to arrive.
It seems there's a new bug with DOSBox .73. In order to install GUS, you need to go into your config file and change the Sound Blaster section to read like this...
sbtype=none
sbbase=220
irq=7
dma=1
hdma=5
sbmixer=true
oplmode=auto
oplemu=default
oplrate=22050
Save the change, then it should install fine. Once it's done, you can (in theory) re-enable the Sound Blaster section by putting it back to "sb16" for "sbtype".