Upgrading MK III OS and Nav

[raf215]

So after reading the forum and all the MK IV information (which BTW is very interesting reading), I'm looking to do an upgrade to my 2002 X5 MK III system . . . and first off, not in a position to go to MK IV = $$

So OS is SW 3-1/50 (v19) and know that latest/last for MK III is 3-1/63 (v22 or higher). Have downloaded v25 from neiloakley.com.
Nav CD is 2002-1 Southeast . . . yea, I know very, very old.

OK, now if anyone has done MK III update or can let me know how to do it, I'll have a go at it and thanks in advance.

BTW, thanks to X5 Meister for his assistance so far. Ray