Hi Tiny Yarou,
First of all I want to thank you for your efforts. It is a remarkable discovery 
I thought that using the sccconv.exe would change the rom, so it can use scc without the NandemoSCC tool. (Just like with ys1,2 and 3)
So, convert the rom, put scc in slot 2 and the converted rom in slot 1 and then boot your msx.
If you still need the NandemoSCC tool, what is the purpose of the converting tool. I can hear metal gear in scc fine without have to use the convert tool.
@Tiny yarou: Okay, I've tried it with openMSX. I use NMS 8250 with nandemoscc disk and converted metal gear (using option 3), I get syntax error in 0 error. But it's okay, it works fine with Turbo R and I adapted sccboot.rom to match 8kb so it works with openmsx. If anyone needs this adapted rom let me know.
But once again, BIG compliment for you Tiny Yarou, playing metal gear with scc is like a whole new experience Thanx again.
Oh, so I need two ROMs, the patcher and the game! Now I get it.
Luckily I have two MFRs. I'll try it later.
It worked!! I just had to add one step to Guillian's list: configure slot numbers accordingly for the MFRs (slot 1-1 = 85h, slot 2-1 = 86h)
Penguin Adventure with SCC and in R800 is wonderfabuloamazingous!