Mike, i am very interested in making a 5150 block letter preset too. here is my process:
first download and try these two presets for cab simulation using your head as a preamp:
https://dl.dropbox.com/u/5622773/Greenback%20cab.tfxhttps://dl.dropbox.com/u/5622773/Vintage%2030%20cab.tfxboth of these have two components that you may need to tweak to get it to sound like your real cabinet:
try turning off the eq or changing the high freq settings like Q, cut amount or frequency if you find it too dark sounding.
turn off the compressor if it feels too squishy or pushy.
both the eq and compressor are setup to get the cab sim sounding and feeling like my gear in my bedroom. your mileage may vary.
once you get the cabinet sim sounding close to your real cab, save the cab sim preset and email it to me.
next record yourself doing a little playing with the following things: using only one channel and setting....first play a few seconds of lead licks, followed by some crunch riffing, then some clean or blues by only rolling back your guitar volume. this will tell me what type of amp model to use to start with and how much gain i need.
record 3 tracks:
1) clean guitar DI
2) with cab sim preset
3) raw with no cab sim
with all of these components i can get fairly accurate (limited only by the eleven rack's abilities) when making a preset.
once you have everything ready to go, email them to me at:
rossjjohnson@gmail.com
depending on what i have going on, i should be able to get a preset made pretty quickly.
i'm working on the 5150 III preset now with only the raw track to work with, but it's a start.