If your symptoms are like mine, it can't hurt to give it a try:
I usually don't have pain during a BM; it comes about 15-30 minutes later. The spasms, not the pricks and stabs that come with them, but the burning...I can feel it grow from a match tip, to a cigarette, up to a fat cigar. The hot baths don't touch it. But, I made my way here to the computer. I've been here for about an hour and 15 minutes--sitting on my board. If I sit with my weight on the "sitting bones" and press into the spasm while sitting very erectly it provides a counter measure, and I have found that it offers a distraction and some relief. My burning went from constant to transient while sitting here. Usually, three hours will make the spasms become very mild ad tolerable, whereas I was in tears when I first sat down.
I have, as my CRS put it, a significant fissure and extensive hemorrhoids. In spite of the hemmies (internal progressing to external) it helps me some. I absolutely cannot lie down in the bed during these severe spasm episodes.
I know it won't help many of you, as your fissure may not tolerate sitting much at all. But I found that for me hard surfaces help and soft surfaces aggravate the condition.

Interesting. I have found at times sitting in certain ways on an exercise ball helped too. Can you be more specific with how you're sitting and how you maneuver yourself into it?

That is v interesting.....@ Anonymon - Salt Bather - I too have found relief after sitting on an exercise ball too and always make sure I sit on a cushion when driving on indeed when sitting in work for 5-6 hours straight. I also find that if I am pre-occupied I too get distracted and the pain seems to go away...when you are on your own and thinking about the pain it always seems worse.........walking also nearly always get my pain down from a high 8 to a 1 or 2, I think exercise gets the blood flowing ! Good luck to you all

As a new member I can't post external links yet, so try to read through my disguised url's.
This page may help:
youasamachineDOTcom/anatomy-101/q-a-sitting-bones/
And this shows how I look in my chair, though I'm a big lady at a computer =):
back-pain-self-helpDOTcom/lower-back-exercise-find-sitting-bones.html
I went to bed last night to have my spasms return. I ended up sleeping in the hot bathwater.
And yes, walking helps so much.
I drive (minivan and school bus) sitting very upright on a plywood board (9X9). I used to sit slumped with my weight to the rear of my pelvis, NOT anymore!
I will be so glad when one day I can post my success story.

I sit on wooden chairs, preferably flat, whenever possible as well, momof7. Elsewhere I've seen people explain it as not spreading the fissure apart. Squishy chairs are awful but my couch is pretty firm and I can tolerate that much of the time. I sat on books in the car a lot because they were handy.
Putting a square of plywood in there is a good idea and will save me some pain - thanks!

Trial and error is the best thing to do when dealing with fissures, any ideas about how to deal with the pain and suffering will help others find a way to minimize discomfort.
When my fissure was fresh and irritated with 24 hours spams, I learn to let go of the muscles that control the anal area, just like doing strenghthening exercises for the pelvis floor that help me relax the sphincter and ease spams, I did this during those painful sleepless nights.
Then alleviate the irritation after BM I lubricate the anal area with Vaseline, that minimize friction on the fissure wound, stools are very irritating when passing over a raw fissure.
My fissure is 10 months old and still having set backs but living more comfortable and yes I have done almost everything to get the fissure under control just like most sufferers out there, trial and error and lots of good advise.
So keep them coming, everything helps .

to FLhopeful: Glad to have given you a good idea. My board is inside a pillowcase. =)

walking is the best thing i have found for spasm relief. a half hour walk after bm. and then try to keep moving all day. don't sit down until evening...!