Perhaps, this is what you're looking for. Please see the bolded text for something that you say to a Bhikkhu to help him, in the case that you're not a steward but just a layperson interested in donating.
Footnote 105:
"The Buddha had to steer a middle course between
honoring the laity's generosity and concern for the welfare of the
Bhikkhu-Sangha and preventing the bhikkhus from receiving and using
money. Thus, while bhikkhus are not allowed to receive money for their
use, they are allowed to accept things obtained from a
properly-deposited fund. This is usually done through the services of
a monastery-steward who is entrusted with money provided by lay
people. In our modern, money-dominated world this may appear as a
subtle and refined point, however, it may be helpful to compare this
arrangement to a special Trust Fund from which the beneficiaries (in
this case, bhikkhus) can only receive material requisites. That is,
the donor (temporarily) establishes a Trust Fund to provide a bhikkhu
with requisites through the monastery-steward as manager." (HS ch.14)
"...the Buddha permitted money to be entrusted by a donor to a
steward, who may be a monastery attendant or a lay follower, for the
personal benefit of an individual bhikkhu, thus:
'There are, bhikkhus, people of faith and confidence (in the Sangha)
who entrust money into the hands of monastery stewards saying, "With
this, provide the bhikkhu so-and-so with what is allowable." I permit
you, bhikkhus, to accept an allowable item obtained thereby. But this,
bhikkhus, I do not say: that in any circumstances may gold, silver or
money be accepted (by a bhikkhu, or) be looked about for (by him).'
"When the donors ask the bhikkhu, 'Has the Venerable One a steward?'
or, 'Is there an appropriate place where I may deposit this money,' or
some similar question, then the bhikkhu may point out a suitable
steward, or he may indicate an appropriate place. Should the donor
deposit the money with that steward, or in that place, then it is
properly deposited." (AB)
Footnote 106:
"Money given to a steward of the Sangha
(veyyaavaccakara), for the use of bhikkhus or to stewards of
individual bhikkhus, is not given to the bhikkhus for them to possess.
The steward holds the money of the donors in trust, and should a
bhikkhu have legitimate reason to make use of this (travel for Dhamma,
Requisites, Dhamma-books, etc.), he can request the steward to supply
him with the article needed. He cannot purchase it himself. "This rule
concerns money of which a bhikkhu has such thoughts as, 'It is mine'
or 'It belongs to me' and which he intends to use for purposes other
than those of Dhamma." (Paat. 1966 Ed.; p104-105)
Footnote 107:
"The Monastery-Steward: The monastery-steward is usually someone who
is a close supporter of the monastery. Not only should he/she ideally
be well-informed about the monastic guidelines relating to money, but
also be knowledgeable about what is appropriate to provide and the
proper procedures for doing so.
"When a fund has been properly established and the bhikkhu is in need
of a requisite, he may approach that steward and state what he is in
need of. Should a bhikkhu command the steward to: 'Buy me this,' it is
considered a case of dubbhicaritata (wrong procedure) and that bhikkhu
may not make use of any article obtained therefrom, although other
bhikkhus may use it.
"It is a fault of Acknowledgement with Forfeiture [Nis. Paac.10] for a
bhikkhu who receives a requisite by badgering the steward beyond
verbally reminding him three times and standing silently up to six
times. If the required requisite is not forthcoming the bhikkhu is
obliged to inform the donor that the invitation to requisites has not
been fulfilled. The Commentary says that if the bhikkhu does not
inform the donor it is a fault of Wrong- Doing "for breaking a
custom"). The donor may then take up the matter with the steward." (HS
ch.14)
"A bhikkhu may not command (tell) either the donor or the steward what
to do with regard to the gift of gold or money. However, he may give
them hints, or suggestions, or any information, as long as these fall
short of ordering the donor or steward. Also, a bhikkhu may not accept
the ownership of gold or money offered to him indirectly, for example
should a donor say to him, "In such and such a place is a certain
amount of money, I give it to you." then the bhikkhu is obliged to
reject the gift by words or by a gesture of refusal or by mental
resolve (e.g., determining, "I do not accept this") otherwise he
incurs [an offence of Confession with Forfeiture]." (AB)