110 modifications
You have to start somewhere!
Two things to keep in mind:
1) I don’t always know what I’m talking about (!)
2) I don’t have a DR-110
but, judging from this:
http://www.cykong.com/Synths/Boss DR-110/Images/Boss DR-110 Schematics b Voice.gif
it wouldn’t be too hard at all to make individual outs for BD, SD and Clap, I can’t tell where you could pick up the individual HH and Cy signals. The dead easiest to do would to put a switching jacks in for SD, BD and all the HH/SY together.
For the SD you’d need to find a place to cut a trace that is between between the nexus of R71/R85/C36 and the Balance pot. The switching jack would be wired to complete the cut trace when closed (tip to the R71/R85/C36 nexus, normal to the pot.)
For the BD do the same between the balance pot and a point common to R86/C46.
HH/CY are on the other side of the balance pot, put the switching jack between the pot & a common point of R88/R89.
Use 1/8” jacks since the 110 is so tiny. When the jacks are in use the sounds would dissapear from the mix out.
Trigger I/O might be harder, maybe the 110 uses 6V lines that go to 0V when triggered. The clap has 3 quick triggers and one other (decay?) which would be hard to replicate or use externally anyway.
This is all fascinating theory, but I could be way wrong. You might be better off continuing to make music instead of being an armchair technician like myself.