[R] Having two different versions of a package in the same R installation

[Søren Højsgaard]

Dear list,

I am making some comparisons of two versions of the lme4 package: The CRAN version and the R-Forge version. For the moment I have two different R installations, each with a different version of lme4. However it would be convenient if I could have the same version within the same R installation such that I can run a code chunk on one lme4 version and immediately after run the same code chunk on another lme4 version. Does anyone know if this is possible?

Best regards
Søren