Regarding 401K (Roth, Regular, or Post-tax) can only be funded though your payroll.
Now onto the IRA, a good document is IRS Publication 590-A Contributions
to Individual Retirement Arrangements (IRAs). it includes several times that contributions must be in cash:
Individual Retirement Account
An individual retirement account is a
trust or custodial ac- count set up in the United States for the
exclusive benefit of you or your beneficiaries. The account is
created by a written document. The document must show that the ac-
count meets all of the following requirements.
The trustee or
custodian must be a bank, a federally insured credit union, a savings
and loan association, or an entity approved by the IRS to act as
trustee or custodian.
The trustee or custodian generally cannot
accept con- tributions of more than the deductible amount for the
year. However, rollover contributions and employer contributions to a
simplified employee pension (SEP) can be more than this amount.
Contributions, except for rollover contributions, must be in cash.
See Rollovers , later
When Can Contributions Be Made?
As soon as you open your
traditional IRA, contributions can be made to it through your
chosen sponsor (trustee or other administrator). Contributions must
be in the form of money (cash, check, or money order). Property
cannot be contributed.
Although property cannot be contributed, your
IRA may invest in certain property.
But what about Roth IRA?
What Is a Roth IRA?
A Roth IRA is an individual retirement plan that,
except as explained in this chapter, is subject to the rules that
apply to a traditional IRA (defined next). It can be either an ac-
count or an annuity. Individual retirement accounts and
annuities are described in chapter 1 under How Can a
Traditional IRA Be Opened?
the rest of that section have to do with can you contribute, how to convert an IRA to a Roth IRA
Non-cash items can be purchased and held by the IRA, they can be rolled over into an IRA, and they distributed, but all contributions must be in cash.