http://www.powerlabs.org/chemlabs/nmannitol.htm
Can I just replace the mannitol with erythritol in his reaction?
I'm using 70% nitric acid, and 98% sulfuric acid.
I'm not sure on how to perform this, because the reactions I found on roguesci and sciencemaddness use 99% nitric acid.

Does anyone have a tutorial, or at least some hints?
Would dissolving the erthritol in in the nitric acid and then dripping the sulfuric acid with a burret work?
How much time do I let the reaction proceed, and at what temperature should I keep it?

Also, I intend to use a magnetic stirrer, and a crushed ice/ammonium nitrate icebath.

Just do the math from a synth that uses KNO3 and find how much 100% HNO3 is produced by H2SO4 + KNO3 --> KHSO4 + HNO3. 1.5x that is 70%.

ok, i just ended up using JDP's procedure, scaled down to 1/2.
lets see what happens.

"No incompatibility I have ran into thus far.
My synth for the 60g ETN nitration was 90mls HNO3,
180mls H2SO4, 30g erythritol,
mix the acids in a beaker of suitable size,
chill to around 10C, and add erythritol slowly but not too slowly
(about a table spoon at a time), monitor temp, don't let it go over 25C,
then once all the E is added, let it chill then leave it for around a half hour
with occasional stirring. I use Rooto for all my nitration too. IMO it's the best
drain cleaner H2SO4 out there. HNO3 doesn't lower the yields at all, however it does seem
to decrease yields of MHN when producing larger batches."

i said this to you in IRC but i'll say it again just in case anyone here knows better:

I've always heard (and it makes sense) that with nitration of sugars, the sugar is usually dissolved in nitric acid or stoichiometric H2SO4/xNO3 first, and then H2SO4 is dripped in which controls the reaction. Otherwise the sugar would get dehydrated too easily from exposure to sulfuric acid.