Handling 401ks

[Matt Armstrong]

I'm wondering how to best handle this situation in gnucash:

Each month, X dollars is deducted from my paycheck and stuck in my
401k.  (currently, I have these going into an account of type Bank)

Each quarter, the 401k company tells me how many dollars I contributed
that quarter as well as the beginning and ending dollar value.  They
do not tell me how many shares I started with or now have, nor do they
give a share price.  (currently, I have no idea how to model this in
Gnucash)

Any suggestions?