- AをBに（して）: with A as B; using A as B (See this)
- よりどころ (noun): (lit. "place to rely on") thing one can believe in; (mental) crutch; supporter
- 希望をつなぎとめる: (lit. "anchor hope") keep having whatever small hope
The main structure of the sentence:
The side (=person) which was criticized (i.e., the author of the work) can still have small hope.
And the followings are two subordinate clauses that each modify the verb つなぎとめる:
even if (his work) is spoken ill a bit
using the part which was praised as a crutch
The whole sentence roughly means "(If there are parts that were praised in your work,) Even when some parts of your work are spoken ill of, you can still have some hope using the praised part as a crutch."