  We have used millisecond pulsars (MSPs) from the southern High Time
Resolution Universe (HTRU) intermediate latitude survey area to simulate the
distribution and total population of MSPs in the Galaxy. Our model makes use of
the scale factor method, which estimates the ratio of the total number of MSPs
in the Galaxy to the known sample. Using our best fit value for the z-height,
z=500 pc, we find an underlying population of MSPs of 8.3(\pm 4.2)*10^4 sources
down to a limiting luminosity of L_min=0.1 mJy kpc^2 and a luminosity
distribution with a steep slope of d\log N/d\log L = -1.45(\pm 0.14). However,
at the low end of the luminosity distribution, the uncertainties introduced by
small number statistics are large. By omitting very low luminosity pulsars, we
find a Galactic population above L_min=0.2 mJy kpc^2 of only 3.0(\pm 0.7)*10^4
MSPs. We have also simulated pulsars with periods shorter than any known MSP,
and estimate the maximum number of sub-MSPs in the Galaxy to be 7.8(\pm
5.0)*10^4 pulsars at L=0.1 mJy kpc^2. In addition, we estimate that the high
and low latitude parts of the southern HTRU survey will detect 68 and 42 MSPs
respectively, including 78 new discoveries. Pulsar luminosity, and hence flux
density, is an important input parameter in the model. Some of the published
flux densities for the pulsars in our sample do not agree with the observed
flux densities from our data set, and we have instead calculated average
luminosities from archival data from the Parkes Telescope. We found many
luminosities to be very different than their catalogue values, leading to very
different population estimates. Large variations in flux density highlight the
importance of including scintillation effects in MSP population studies.
