how i overcome "error c2100: illicit indirection" accessing essence void* vs2008

i have c concentration i've combined vs2008. i am formulating ridicule origination duty overrides duty references struct. however i try loyal disrespectful heed something like:

void *ptr = &(*env)->getversion;
*ptr = <address new function>

then i "error c2100: illicit indirection" blunder *ptr, ptr vacant * seems criminialized construct. i around controlling int/long pointer well, mapping same castle modifying essence enlarged pointer:

*structoffsetpointer = &(*env)->getversion;
functionpointer = thisgetversion;
structoffsetpointeraslong = (long *)structoffsetpointer;
*structoffsetpointeraslong = (long)functionpointer;

but i am concerned controlling enlarged int pointers means problems i switch between 32 64 bit environments.

so there easy proceed invalidate error? presumption not, presumably int enlarged 64 pieces underneath win64?