Parse query string parameters in eVars using processing rules

I have a client that is running an out dated s code version with a channel manager plugin that is not supported. While the plugin does still capture the campaign id, it doesn't parse the contents of it into the correct evars.

What I am wondering is if we add additional parameters to the query string as below, can we use processing rules to parse those values into an evar?

As an example the query string might be:

?cmpid=test&cmreferrer=Google&cmsource=Paid&cmmedium=PPC&cmcontent=Branded

What we'd like to happen is to have:

cmpid=test stored as campaign first/last
cmreferrer stored in evar 48
cmsource stored in evar 49
cmmedium stored in evar 50
cmcontent stored in evar 51.

Is accomplishing this with only processing rules possible, or do we need to use java script to parse them?

Thanks!