Move the mic around? Sounds like an algorithym in what ever software it if you're using to me as opposed to one impulse that contains various points, I'm pretty sure impulses are made up of single points as opposed to multiple and that works fine from my experience as no one moves my mic about at gigs.
If I want a different mic sound I pic say the IR of celestion GT75 - sm75 centre 2 inches from grill or pic celestion GT75 - sm75 centre 3 inches
I don't have impulses made up of multiples impulses, this seems like an odd concept to me. I'm pretty sure it's impossible actually unless you brough IR's into a daw and over lapped them but I have no idea why you would do this. I know red wirez impulses are all individual impulses and any other IR i have used is the same, they contain one set of information for what the tone will be like at that moment.
Actually, impulse-based technology is basically merely a variant of Fourier transformation, or, in our case, inverse Fourier transformation.
As such it is simply a series of discreet measurements, fed to a filter with a large number of poles and zeros, or, on more practical terms, corresponding to a large number of filter steps.
Impulse technology is also used for calculating i.e. how a suspension bridge handles varying loads in windy conditions.
Some, or, it seems to me, a few, use up to 2048 samples, and maybe at a high sampling rate, while others may use as few as 256-512 samples.
Now, it is essentially a series of discrete samples, it really isn't infeasible to 'simply' run calculations on several sets of samples, thus essentially merge them.
I don't have i.e. the Two Notes software, but it is my understanding they actually have software that allow doing this - or am I thinking about Kemper..
From this also follows that it really shouldn't be that difficult recalculating the captured impulse to mimick the effect of moving the microphone.
WRT generating the impulse file, anything can be used, actually, like a sine. a sine sweep, white or pink noise, a real guitar or actual music - I think Art of Noise or Heruntergestürtzenden Neugebauten (speeling?) or maybe even pr0n sounds [sic] might make for some interesting impulses
Jokes aside, Kemper actually starts the generation of capturing an amp's characteristics by running some sweep and other weird sounding stuff through it.
After this follows the finetuning, where you'll plug your guitar in and run actual guitar sounds through, this being for fine tuning the generated impulse to best match up.
How i.e. Two Notes does it, I don't know; only that they use 2048 samples at 96 kHz.