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