I'm afraid that is not physically possible. A HST-palette image consists of three bands, namely S-II, H-alpha and O-III, mapped to red, green and blue respectively (e.g SHO:RGB).
The L-enhance filter records Ha, no S-II and records H-beta and O-III lumped into one band. E.g. you are short one band, while to O-III band will be mixed with H-beta signal as well.
The best(and most popular thing to do) you can do, is to create a bi-color as suggested in this thread.
A red/cyan rendering HOO rendering is the most popular as it shows where Ha emissions are, and where O-III/H-beta emissions are, while also roughly corresponding to their location in the visual spectrum.
So (in 1.7) load your data like this in the Compose module; Process your image (in mono), then, once you hit the Color module, use the Bi-Color preset and tweak to taste. Note you can use the Matrix option to flip between other popular channel mappings besides HOO (a feature unique to StarTools thanks to Tracking and being able to do color calibration so late in the workflow). Be prepared for a lot of blue stars as stars don't show up well in Ha (but do so in the O-III through Hb part of the spectrum).
Shrink the stars if you want and/or push them back with the Super Structure module.
Hope this helps!