Building the enlarger from a current 8x10 camera is not to complicated. A film holder can be as simple as two pieces of AN glass sandwiching the film and taking the place of the ground glass. The real bug-a-boo is the light source. Aristo lists an 8x10 cold light head for 8x10 elwood enlargers for $546 and a 10x10 for a Durst for $1200. One could manufacture a collar to secure the light source to the camera and you are ready to go.

Easiest thing to do is to make an easel to put on the wall and hold the paper in place with magnets or thumbtacks. Mount the camera/enlarger to a table. If you are going to use only one size of enlargement the bellows extension will provide critical focus. Just determine the distance from the paper you need for the lens you will use. Make sure everything is square and level. Film plane must be parallel with the paper and a line going from center of the film to center of the paper must be perpendicular to the film plane, lens and paper. Even if you have to buy the 8x10 head (I think both heads are for graded paper) you would have an enlarger for little more then that plus the cost of lens.

I don't know what your budget is, but if it is limited, use the camera for printing sessions and buy the best enlarging glass you can afford.