r-help, how can i use my own distance matrix without using dist()

Dear R-helpers,

i am a beginner of R and i am using cluster package to do hierarchical
clustering

i am wondering if i can use my own distance matrix to do the hierarchical
clustering without using dist() function.

if i have my own distance matrix, how can i ask hclust() function to recongnize
it( as the output of dist() function).

thank you very much and i looking forward to hearing from you.

Marshall