Set spindle speed

I've just spent an unfruitful few hours searching through the HAL stuff to write a simple spindle speed set routine.
HALUI allows me to increment and decrement it in 100s but nowhere can I put in 350rpm and get it.
Is it so obvious that I've missed it?
Can I make the HALUI steps smaller, 10 or even 1, and 'buzz' it up and down?
There is an 'Increment=' value for a spindle0 in the INI but changing that from 100 didn't help.
Can I fake up an S command?
I'm sure you smart guys have done it and I must confess it is to use the mill for a pretty deviant job not pure metal cutting but...

You can certainly issue "S" commands in MDI mode

Yeah got it.
I git cloned the source and as it's C and I've been reading C see since K&R was the hot book to have (like 50 years) it didn't take long.
Track back and discover it's in the NigMill.ini file
but   but  didn't I try that already?
Recheck. There was a section So I just whipped off the # on the first and last line and retried it, got nothing.
Sad. Miserable.
However the dyslexic old coot that I am missed the real section name was SPINDLE_0 and it works. I can increment and decrement in 1rpm steps.

Humm,
Still needs thinking about. I can't click things fast with the interface. What would be nice is to be able to set the increment step live. The system can obviously handle large steps and do all its rate stuff but I can't supply a variable step.
I guess I'll have to get the git source to compile but I believe I need a 2.9 version to suit the Pi not bleeding edge so it might be a bit of a job to add and extra call into linuxcnc/src/emc/motion/command.c and then feed it back through the layers to a pin.
More head-banging to come I guess.