I got it working quite well /reliably by using a digital i/o pin linked to a rail-to-rail op amp used as a comparator that references a constant low voltage (sufficient to change its output for logic 0 and 1 for 3.2 volt axoloti logic signals.) Op amp: MCP6004 is good. It is powered from the 5V Eurorack rail (so it outputs a solid 0V or +5 V as high and low). This ends up being equivalent to a logic buffer with quite good current drive capability, so you can send the signal to passive mults etc. The comparator simply references (‘compares to’) a fixed low voltage from a divider (you want lower than the 1.65 volt Axoloti midpoint reference but not too low to avoid noise, I think I compare to 1V.
I used small capacitors on the outputs I think, to smooth the edge transitions very slightly to give some additional noise exclusion. It works really well for me and with an MCP6004 you get 4 pins of Axoloti-to-Eurorack gate goodness, so I generally link one to midi clock, and the others to either a multiple or divisor of the clock, or to be gates gate for note events or drums etc. Happy circuiting!
Edit: Ahh, sorry, I addressed the hardware side without answering your questin about midi clock objects. For me in software there was some finagling to get a desirable outcome and very little info available about how to do this. I do not remember off top of my head in software what I did to get a midi clock going out, will have to invstigate and follow up.