Hi,
As I said, I'll try to make VST host opcodes for csound. Does anyone
foresee any major pitfalls or problems for doing this?

Here's my syntax proposal for VSThost plugins in csound:

-VSTplugins and intruments would be loaded into memory at init time with 
a global opcode such as:
giVSThandle VSTinit iplugin, [i1, i2....ix]
iplugin is the path and name of the vst dll.
i1 - ix are the initial parameters for the plugin (possibly parameter 
number/value pairs)

-VSTplugins would be called inside an instrument
a1 [,a2] VSTplug giVSThandle, ain1[, ain2]
a1 [,a2] VSTinst giVSThandle, ain1[, ain2]

-There should be an opcode to open the graphical interface for the plugin:
editVST giVSThandle

-There should be opcodes for MIDI communication to and from the plugin
kdest VSTctrl7 giVSThandle,ichan,ictrl, imin, imax [,ifn]
VSTmidiout giVSThandle,kstatus, kchan, kdata1, kdata2

optionally:
kstatus, kchan, kdata1, kdata2 VSTmidiin giVSThandle
VSTmidion giVSThandle,kchn,knum, kvel

Any thoughts?

Andrés