If when i compile my script, i try to use the MD5 space (calling 'package require md5'), and get a 'cant find package' error... is there anything I can do, if i dont own the server?
md5 is indeed a part of tcllib. tcllib, however, is not part of the tcl/tk project, but an external package providing extended features. You can find the project at sourceforge, and it is a tcl-only library - meaning it requires no compilation but should run straight out the tar ball (apart from setting up library search paths I suppose).
If you wish to use the tcllib version of md5, grab a copy from sourceforge, unpack to your favourite directory, run the installer and specify locations to install packages, examples, binaries, etc; and add the location of the packages to the tcl_pkgPath list-variable before calling "package require ...".