Along buffer size, you need to change in hid_desc.bas:
Code:
ReportDescriptor1
	retlw   0x05
	retlw   0x01    ; usage page (generic desktop)
	retlw   0x09
	retlw   0x06    ; usage (keyboard)
	retlw   0xA1
	retlw   0x01    ; collection (application)
	retlw   0x05
	retlw   0x07    ;   usage (Key codes)
	retlw   0x19
	retlw   0xE0    ;   usage minimum (224)
	retlw   0x29
	retlw   0xE7    ;   usage minimum (231)
	retlw   0x15
	retlw   0x00    ;     logical minimum (0)
	retlw   0x25
	retlw   0x01    ;     logical maximum (1)
	retlw   0x75
	retlw   0x01    ;     report size (1)
	retlw   0x95
	retlw   0x08    ;     report count (8)
	retlw   0x81
	retlw   0x02    ;     Input (data,variable,absolute)
	retlw   0x95
	retlw   0x01    ;     report count (1)
	retlw   0x75
	retlw   0x08    ;     report size (8)
	retlw   0x81
	retlw   0x01    ;     Input (constant)
	retlw   0x95
	retlw   0x05    ;     report count (5)
	retlw   0x75
	retlw   0x01    ;     report size (1)
	retlw   0x05
	retlw   0x08    ;     usage page (page# for leds)
	retlw   0x19
	retlw   0x01    ;     Usage minimum (1)
	retlw   0x29
	retlw   0x05    ;     Usage maximum (5)
	retlw   0x91
	retlw   0x02    ;     output (data,variable,absolute)
	retlw   0x95
	retlw   0x01    ;     report count (1)
	retlw   0x75
	retlw   0x03    ;     report size (3)
	retlw   0x91
	retlw   0x01    ;     output (constant)
	retlw   0x95
	retlw   0x06    ;     report count (6)
	retlw   0x75
	retlw   0x08    ;     report size (8)
	retlw   0x15
	retlw   0x00    ;     logical minimum (0)
	retlw   0x25
	retlw   0x65    ;     logical maximum (101)
	retlw   0x05
	retlw   0x07    ;     usage page (keycodes)
	retlw   0x19
	retlw   0x00    ;     usage minimum (0)
	retlw   0x29
	retlw   0x65    ;     usage maximum (101)
	retlw   0x81
	retlw   0x00    ;     input (data, array)	
	retlw   0xC0    ;   end collection
EndReportDescriptor1
If I understand correctly. But I never had any luck with changing descriptor files.