The AVRISP programmer is AVR ICP910 based on the AVR910.ASM application note.
The old ICP910 does not support Mega chips. Only a modified version of the AVR910.ASM supports Universal commands so all chips can be programmed.
The new AVRISP from Atmel that can be used with AVR Studio, is not compatible! You need to select STK500 programmer because the new AVRISP programmer from Atmel, uses the STK500 protocol.
When you do not want to use the default baud rate that AVR910 is using, you can edit the file bascavr.ini from the Windows directory.
Add the section [AVRISP]
Then add: COM=19200,n,8,1
This is the default. When you made your own dongle, you can increase the baud rate
You need to save the file and restart BASCOM before the settings will be in effect.