I am not sure if I understand your request fully. Do you want exact (integer) BPMs? You will have to use the modern tempo mode (which is incompatible with IT/XM) to get real integer BPM tempo.

Just for more tempo precision in live use between different computers and hardware without MIDI sync. and mouse wheel for real time adjust.

I'm still not sure if I fully understand. Do you want tenths and hundredths of BPMs? Which hardware supports non-integer BPM tempos?

yes tenths and hundredths of BPMs, just because the clocks of different devices have always some offsets without MIDI sync.
am i the only one using OMPT on the fly in real time ?

Do you use modern tempo mode? If your MIDI hardware isn't precise enough to support exact BPM settings, it's probably not worth using after all. :P
I have no problem syncing OpenMPT to my synths in modern tempo mode.

i use modern tempo mode but, for explain, in impro live use on stage for example with some people you don't know, and without midi sync.

I think he meant that he wants to make a song with tempo 125,58 or similar to that.

Starting from r5217 / OpenMPT 1.25.00.10, fractional tempos can now be specified for the default tempo and the instrument pitch/tempo lock in the MPTM format. Currently there is no way to set a fractional using the Txx command (except tempo slides, which retain the fractional part of the tempo).
Grab a test build to see how you like the implementation at http://buildbot.openmpt.org/builds/

Quick test.
it looks perfect.
just in the general tab we can change the tempo with the mouse wheel.
but not the fractional tempos.
or I didn't find how.

thx Saga !!
:)

Well, right now the mouse wheel does 1 BPM increments. Doing .0001 increments (internal maximum resolution) seems a bit odd to me. What would you suggest as a granularity here?

.1 would be nice
.01 would be wonderful
and really nice for live playing.

the same thing could be possible in the toolbar's tempo ?

Alright, scrolling or using the spin buttons now uses .1 increments, and holding shift reduces it to .01 increments. Note that the latter only works with the spin buttons though, it magically refuses to work when using the scroll wheel.
buildbot still requires a while to run but r5221, once it's up, will have these changes.