Ja, kann man durchaus so sagen.

Pons-Collins:
to dot one's i's and cross one's t's - (fig) peinlich genau /or/ penibel sein

Oxford-Duden;
dot the i's and cross the t's - (fig.) peinlich genau sein

NOAD:
dot the i's and cross the t's - [informal] ensure that all details are correct.

This example is actually an overlong paraphrase of a much shorter idiom, namely, 'to dot ... I's and cross ... T's.' It can be used in either a positive or a negative sense.

It can be expressed in several forms: 'to dot one's I's,' 'to dot the I's,' 'to dot all the I's,' 'to dot every I,' etc.

Technically, if you use lowercase for the letters I and T, you should italicize them, otherwise use uppercase. But sans-serif fonts like LEO's Arial make capital I look like small L.