P60 refers to a standardized drop in module made up of a reflector and pill that screw together and “drop into” a large number of hosts made to fit them. Most are still single led versions sold in various DIY market places but there are custom prebuilt triple and quad P60 modules sold as well. To DIY one you need a P60 host such as Solarforce L2() or Ultrafire 50(1,2)b among others, a shell made for either a triple or quad, an optic and matching mcpcb that fits the shell, and a driver to control them.
I haven’t been able to find any info about the VG10 triple/quad 
Would a spacer need to be built?
Not really. Suefire (haha) had a system of incandescents which needed to be quickly replaced in the field, so they had the P60 (6V) modules and P90 (9V) modules (based on the number of stacked CR123s).
That form-factor was quickly adopted for LED replacements, and became the de facto module for a bunch of different hosts and modules to let you plug’n’play a whole bunch of flashlights.
That gave rise to the little-used (unfortunately) designation D26 (for 26mm across). But, most people still call ’em P60s or P90s.
So D26 is related to the dimensions, but not P60 or P90 (voltage).
And since a Li cell is neither 6V nor 9V, P60/P90 makes even less sense than D26, which is perfectly descriptive. Call it a D26, and you’ll get looks like you just sprouted a 2nd head, though.