I do not see how you can do it in your select-statement, but using a regexp in VB-script makes it possible.
set o = new regexp
o.global = true
o.pattern = "(([a-zA-z0-9])*([\ \,\.])*)"
t = rs("yourColumn")
Set Matches = o.Execute(t)
if matches.count > 29 then i = 29 else i = matches.count
response.write mid(t,1,matches.item(i).firstindex+matches.item(i).length)
Probably the pattern may be written in some other manner and you may wish to add some extra characters that delimits words. (I'm rather new to regexp.)
red: Some hatched variable names