bigbadron:
Unfortunately the sheets here are just simple text documents. While you can post links into them, mathematical functions are beyond their capabilities.
The closest you could get would be to upload your sheet elsewhere, then link to it from the character sheet here.
This brings to mind an interesting follow-on question:
Can character variables in the RPoL character sheets be expressed as HTML links to corresponding cells in a spreadsheet hosted elsewhere such that when the spreadsheet is updated the link in the RPoL sheet shows the updated value?
That might be a worthwhile experiment. It might become something akin to cross-site scripting, though, and pose a security vulnerability.
Aside from the technical question, would such linking be in conformance with RPoL's terms of service? (I don't want to attempt any experiments regarding this if it's not permitted.)