ISIS V5.6 integrate now a very simple version of personal spectral database, see here:
http://www.astrosurf.com/buil/isis/new/release.html
The example taken is ELODIE V3.1.
(specific to ELODIE V3.1 LL: you have to convert to relative flux near unity value for instrumental response calculation. Also, the continuum down to 4000 A is clearly uncertain in ELODIE V3.1 base).
Christian Buil