Before you embark on that rewrite, check carefully that you can indeed install and run all you need. For example, if they are no already installed, most DBDs (the layer of DBI that actually interact with the DB engine) need to be compiled and linked against the DB libraries. Same for most image manipulation tools, or XML parsers.

Others that use the same hosting service could probably give you a useful list of what's available, and what they were able to install themselves.