The following MATLAB script uses the Delsys file utility to convert an input HPF file to CSV and then load and plot it in MATLAB.
function [ ] = plotdata( file 
)
    dos(['"C:\Program 
Files\Delsys, Inc\EMGworks 4.0 RC4\DelsysFileUtil.exe" -nogui -o CSV -i ' 
file]);
    data = csvread([file '.csv'], 1, 
0);
    plot(data(:,1), data(:,2));
end