Adding floating point precision to qnorm/pnorm?

Question

I would be interested to increase the floating point limit for when calculating qnorm/pnorm from their current level, for example:

x <- pnorm(10) # 1
qnorm(x) # Inf
qnorm(.9999999999999999444) # The highst limit I've found that still return a <<Inf number

Is that (under a reasonable amount of time) possible to do? If so, how?