Do you have a PicKit 2 or 3?
You can set the MR-16 start channel with either of them.
From my own experimentation, this will set your start channel.
Step 1, load the MR-16 firmware. Verify the correct checksum
Step 2, scroll the screen down to row "A00"
Step 3, in the table below, from the first column, choose your start channel
Step 4, change the "0001" that is there to the second column value
Step 5, write the firmware to your PIC
NOTE: the checksum will now change. (that's why I had you verify it in step 1)
First column = "Standard" Start Channel numbers
Second column = Value to enter at A00
1 0001
17 0011
33 0021
49 0031
65 0041
81 0051
97 0061
113 0071
129 0081
145 0091
161 00A1
177 00B1
193 00C1
209 00D1
225 00E1
241 00F1
257 03FF
273 13FF
289 23FF
305 33FF
321 43FF
337 53FF
353 63FF
369 73FF
385 83FF
401 93FF
417 A3FF
433 B3FF
449 C3FF
465 D3FF
481 E3FF
497 F3FF
As far as "testing" the MR16 after the change, I use my Bobcat DMX tester. If you didn't get one in the last COOP, it has been great for use out in the yard to turn on specific items and so many other things.
If there is ever a version made to output PixelNet, I'll jump on that one, too!!! It will need more digits!