external grant on application for SLAC/PUI I am looking for tenure track faculty position in a hard science field at 4 year colleges.

Recently a grant application, which I worked on as a postdoc, was successfully accepted. I am not a PI but by supervisor is willing subaward part of it to me when I get a new position.

My question is how do I refer to this in my cover letters?  Will this set me above other candidates or is it not that important? Would making a big deal out of this look like I'm not as interested in teaching as in research?

What are external grants typically used for as these type of institutions where you don't have grad students or post-docs? Besides travel/conferences would it be to funding undergrad research and summer salary?
Four-year colleges are extremely diverse as to their educational philosophies, attitudes toward faculty research, and financial stability. Do you want to
begin your career at a place that would react unfavorably to this potential
opportunity of yours? @AlexanderWoo's suggestion to 'outsource' the bragging
to your supervisor's letter of recommendation seems sound. But you should
be able to mention this research connection in your cover letter in an
unobjectionable way.

One hopes that cover letters will result in interviews. A common question
in interviews has to do with your ideas how to balance teaching and
research. Your continuing research connection provides a fine opportunity
for you to think how you will deal with that question when it is asked.

Professional travel and participation in conferences can be crucial to
your continuing professional development at a four-year college. You can
hope that the subaward can help with that. On an assistant professor's
salary, you may be very happy for the prospects for some additional
summer salary. 

I wonder whether it's possible to know in advance if or how
you can use these funds for undergraduate research. Obviously, that
depends heavily on the nature of your research and on the quality and
interests of individual students. Not so obviously, it may depend even more
on whether the financial officer handling the subaward at the
four-year college is knowledgeable and flexible enough to handle
paying appropriate students out of subaward funds.